Are you looking for a plugin that lets you use the gamepad, or shows a window when it gets connected?
Using the gamepad should work with no plugin, at least it does in MZ.
Testing in rpg maker the gamepad is not recognized. Maybe exporting as a game it is, I didn't get to test it.
Odd, I thought it was supported by default in MV. Well, in MZ it is supported with no plugin needed, in both exported games and playtest.