Essentials is one of the simplest plugins out there. If you've having trouble with permissions, maybe check out the following video showing how to get started with ranks.
Also, if you have both LuckPerms, Vault, and Essentials installed, you only need the following two commands to give access to tpa for all of your players:
/lp group default permission set essentials.tpa
/lp group default permission set essentials.tpaccept