If you want to use the mod as a plugin, then it is very simple, but there is one thing. The mod uses a localization message, instead of a raw message. And if you just put the mod on the server and log in from a client that does not have these mods, then for example with /afk you will get the message "project_essentials.afk.out_success" or something similar, but not the point.
This problem can be fixed in a very simple step. Find the resource-pack property in the server.properties file and paste this link (below this paragraph) there (this is a resource pack with localization).
If the localization is out of date, run build.ps1, it will automatically download all the localization and pack resource packs in the out folder.
Direct links for Minecraft 1.14.4.
For all modules: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-all.zip
For essentials module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-essentials.zip
For core module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-core.zip
For permissions module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-permissions.zip
For cooldown module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-cooldown.zip
For chat module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-chat.zip
For spawn module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-spawn.zip
For home module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-home.zip
For warps module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-warps.zip
For backup module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.14.4-backup.zip
Direct links for Minecraft 1.15.2.
For all modules: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-all.zip
For essentials module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-essentials.zip
For core module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-core.zip
For permissions module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-permissions.zip
For cooldown module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-cooldown.zip
For chat module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-chat.zip
For spawn module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-spawn.zip
For home module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-home.zip
For warps module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-warps.zip
For backup module: https://github.com/ProjectEssentials/ProjectEssentials-Localization/releases/download/v1.1.0/ProjectEssentials-Localization-1.15.2-backup.zip