Hello everyone! I'm new to Garuda, in fact I only discovered it a few days ago. I would like to know three things:
How do I install Broadcom drivers on Kernel Zen for MacBook?
How to run applications designed for Android?
How to run applications designed for Debian, Ubuntu, and derivatives?
I could probably answer this, but you didn’t post the output of inxi -Faz with ~~~ above and below it.
With an Android emulator. Probably several in the repos and/or AUR.
Do you mean “run applications” (becasue you just run any Linux/X.org app the same way, Debian, Arch, Red Hat, etc.) or “install alien package” like your title implies? (In which case the answer is you are unlikely to need to do so, the repos are quite complete, and the AUR likely has what you want if the repos do not.)
In addition to the above, I’d like to encourage you to use the resources available, for example searching the forum, the web, and reading the Garuda and Arch wikis.
The vast (vast) majority of problems have been faced by someone else already, and the vast (vast) majority of questions have been asked already, so being able to find these solutions and answers is a very (very) useful skill.
You don’t. Arch Linux is its own. Just like Debian is Debian, and Fedora is Fedora and ne’er the twain shall meet.
What Arch and Garuda offer are the same, or nearly so, packages you are used to using in Whatever Linux. Maybe more…57,000 pkgs?..in main and AUR repositories. Maybe more. I lose count.
As Debian uses Dbpkg, so Garuda and other Arch derivities use Alpm. We use Pacman as the package manager, and a variety of AUR helpers.
Digesting this and what the astute @jonathon suggests should keep you busy for a while.
Arch is Arch, and no other. Garuda is an operating system based on and composed of (mostly) Arch packages, put together for you in a nice graphical installation. By some of the best people around. 
Welcome to Garuda Linux!
This ^^^ couldn’t possibly be less helpful.
Open a help request in the networking sub-forum if you wish assistance with networking.
Be sure to include your inxi -Faz output if you desire assistance, without that information finding a solution would be pure guesswork.