Go to the Prism Launcher website and hit the
download button:

Download the installer and follow its instructions.
Open the Prism Launcher, click on the Minecraft Skin icon on the top right,
and hit “Manage Accounts”

Hit “Add Microsoft” and follow the instructions to log in with your
Microsoft account.

#releases channel in the Boundless SMP Discord:
Drag and drop the ZIP file into Prism Launcher.
Hit OK at the bottom right.
You’re now good to go! Double-click the modpack (or hit the launch button) to start.
#releases channel in the Boundless SMP Discord:
Open the downloaded ZIP file with any ZIP software of your choosing (e.g. WinRAR, 7Zip, etc.).
mods folder (i.e. the JAR files inside it) into the folder containing your currently installed mods.