Plugin not Installed in folder plugins!

Hi Aternos . I have a promble . I Need a Inastall a plugin, But this dont inastall in files/plugins. Plugin:

Link: https://aternos.org/addons/a/spigot/13877 &&& https://www.spigotmc.org/resources/13877

I Inasatelled this but i can't see in my folder plugins. pls help!

Plugin Version Inastalled: v1.11.1

Server Version: 1.12.2 [Spigot]