
The Plugins and Mods tab lets you add extensions to your server without opening an FTP client. The screen reads in two columns: on the left the CATALOG, where you search and install, on the right the INSTALLED column, which lists what your server already carries.
At the top of the catalog, a Plugins / Mods toggle switches the source being browsed, and the note on the right reminds you of it: Source: dev.bukkit.org for plugins, Source: Modrinth for mods. The search field changes its prompt at the same time.

Each card in the catalog shows the project's icon, its name, a short summary and its download count. The Details link opens the project's public page in a new tab. The whole card, for its part, is a button: one click displays the available versions.
This list of versions replaces the grid. Each row shows the file version, its compatibility badges (the game version, the loader, or version not declared) and the file size. The INSTALL button does the rest: the file is placed on your server, without going through your machine. Back to catalog takes you back to the grid.
A plugin and a mod do not target the same engine. A plugin requires a Bukkit, Spigot or Paper server; it is placed in the plugins/ folder and picked up at the next start. A mod requires a Forge, Fabric, NeoForge or Quilt server, and the same loader on the players' side; it goes in the mods/ folder. The panel repeats this rule under the search bar, before installation rather than after.
If your server has no mods/ folder, the MODS counter shows a dash, and installing a mod opens the This server does not accept mods window. The steps to follow are written there: install a Forge, Fabric, NeoForge or Quilt version from the Properties tab, start the server once, then come back. The engines are detailed on the versions and modpacks page.
The right-hand column counts your plugins and your mods separately. Each row shows its state, active or disabled, and two actions: the first enables or disables the extension, the second removes it. Removal asks for a confirmation, because the file is deleted from the server: the data it has already written to the world stays in place, but will no longer be read.
The GOOD TO KNOW box, at the bottom of this column, reminds you of three things:
An installed extension is only loaded at the next start. Restart the server, then look at the console in the Properties tab: that is where a plugin that refuses to load explains itself, line by line. The full tour of the screens is on the page the panel, screen by screen, and support answers by ticket.