So you have a group of three that is going to be two matrix types and a mage?
Now, on to your specific problem. First, I'm going to say you ought to throw out any campaign you were thinking of doing, and run some Missions or other modules until you've got a handle on the Matrix and Magic stuff. They like to keep the Matrix and Magic stuff simple in Missions play, which will be a big help to you as you're learning. Just treat it the same as doing pregen characters when you're learning a new system. You're learning to GM Shadowrun, so put the training wheels on until you're confident in your skills. Much better to string several premade modules together into a campaign than trying to learn on the fly while managing your own plots and fail utterly.
Second, I'll give you a primer on Magic (and let someone else give you the Matrix spiel). Mana is basically the Force. It is the energy of life, and it flows through living creatures and the planet itself, connecting life together. A mage or adept is able to tap into mana like someone using a garden hose taps into the water main. The mage or adept would be the sprayer at the end of the hose, shaping mana for various effects.
Now, let's start with what magic CANNOT do. Everything I'm about to talk about are hard stops, as in no way, no how, unless maybe, possibly you're a Great Dragon or an Immortal Elf, and even then the mana levels might not be high enough for it yet. These are things that every magical research group from A to AAA has been working on since the Awakening, and they've got jack squat to show for it.
Magic CANNOT raise the dead. The closest you get is calling something... Other to possess the corpse, and it may masquerade as the former person if that idea amuses it. But these entities are usually quite amused enough just ridding the world of all life they can, in as cruel and sadistic a way as they can imagine.
Magic CANNOT alter space and time. No teleporting. No time travel. No speeding/slowing time. No making wormholes or tesseracts or whatever to go from New York to Los Angeles instantly. There are ways to fake teleportation, but those either fall into the category of 'a great dragon overcast a Levitate spell', or 'someone hopped you over to the astral plane, and you moved at the speed of thought to another point, where you hopped back out of the Astral'. Either of which may LOOK like teleportation, but it is not. Likewise, when you're going to the metaplanes, your perception of time can be wonky. You might spend what literally seems like hours or days on a metaplane, but only minutes have passed in the real world. Or you could have spent what seemed like half an hour on the metaplane, only to come back to a body that is about to die from dehydration. Metaplanes are funky like that. This is not manipulating time, but your perception of it.
Magic CANNOT make a mundane Awakened. You might be a Latent Awakened, and then get your gift kickstarted by something, but mundanes cannot become Awakened. Anything that claims different is usually a powerful spirit that either wants to wear you like a cheap suit, or use you for even less pleasant ends.
Magic items CANNOT be used by mundanes. With the exception of Contact trigger preparations, Mundanes can't even turn magic items 'on', much less make use of them. Foci (including Weapon Foci) have to be bound to an Awakened creature to work. Oh sure, a katana weapon focus still makes a damn fine implement of murder and mayhem without being bound, but the extra specialness doesn't happen unless you bind it. There are rumors about certain items that ignore this rule. These are either Artifacts (capital A) from the Fourth World that are utterly beyond any mortal's ability to replicate (and keeping one is a great way to get a target on your back), or is something Extra Special that was made completely custom through means that are almost certainly unwholesome to contemplate and likely come with intense drawbacks, if you can even get the recipe to begin with. These are items that START with ingredients like 'a fang from a live dragon' and get more difficult to source from there.
Magic CANNOT manipulate the Matrix, and vice versa.
Now that is out of the way, what CAN magic do?
Short answer? Pretty much anything I didn't go into above, but not all at once, and conditions may make things 'difficult'. Magic doesn't interact with technology well, though. And the more tech you stuff in yourself, the harder it is for some spells or powers to affect you, since you're further from 'natural'. Worse, for anyone Awakened, losing Essence (for any reason) is like putting a kink in that garden hose I was talking about earlier. Or perhaps you could say it is like an artery clogged with cholesterol. Sure, there's still blood pumping through that artery, but you got to work harder to get the same result, which can lead to Bad Things
tm happening.
Now, if you're looking for the general 'hows' and 'whys' of magic, I'd skip all the 5E stuff, since it is laid out in a godawful fashion, and go pick up 4E's Street Magic. The basics of magic haven't changed that much since 4E, and they actually laid the books out in a sensible manner back then, so it is a lot easier to get a handle on things. Once you've got the basics from Street Magic, then come back and start looking at the 5E stuff.
I'd tell you to do the same for the Matrix, but the 5E matrix was basically done to make Jar Jar Binks look sensible in comparison.
