CurseForge is an app that will manage the game's mods for you. You can download it here: https://download.curseforge.com/
Once it is installed and running, click on minecraft in the list of games. If it's not already installed, CurseForge will install it for you.
From here, it's just a matter of typing "UwaCraft" into the search bar and installing it! The client will handle the rest.
Clicking "play" on UwaCraft will start the minecraft client with mods enabled.
THANKS MICROSOFT. I can't help you with this one. If this is your first time playing minecraft in years, you will need to turn your mojang account into a microsoft account. It sucks and everyone hates it.
That's it, just go ahead and plonk minecraft.uwa.io into your server browser!