Activating the AUR and building packages with Pamac
Before activating the AUR, it's important to have familiarity with the package build process, as you may need to audit and adjust packages before building them. While most packages work out of the box with Manjaro, some isolated packages may require extra attention.
Furthermore, maintaining AUR packages is the responsibility of the person who installs them, as Manjaro has no control over their contents or how they're packaged. While building and installing from the AUR is officially supported by Manjaro, the quality of the packages is not guaranteed, and they may harm your system or not even build.
It's also important to know how to debug the software you're building in case any issues arise. If the software you're looking for exists in the Arch upstream but not in Manjaro repositories, installing it from the AUR is not recommended, as there may be compatibility issues.
If you don't have any packaging skills using Flatpak or Snap may be a better option. To activate the AUR, launch Pamac and go to Preferences > Third Party, toggle the AUR button, and choose "Check for updates" if you want AUR packages to auto-update with the rest of your system.
Congratulations! You can now search, build, and install packages from the AUR.