What's changed
From a server's menu on your dashboard, search Modrinth, SpigotMC or CurseForge for a plugin, mod or modpack, pick a version, and it installs straight to your server. Plugins and mods go into the right folder automatically; modpacks reinstall the server on Modrinth's modpack egg.
The installer detects your server's Minecraft version and loader (Paper, Spigot, Forge, Fabric, Quilt...) automatically and filters Modrinth results to match, so you only see compatible options.
A SpigotMC plugin whose author only linked an external site can't be auto-installed - those are marked "External" with a link to download it yourself instead.