Install LibAddonMneu-2.o directly into your AddOns directory and remove any included LibAddonMneu-2.0 folders from the subfolders of your addons, e.g. directly in the addon or in another subfolder "libs" etc.

Tell the addon devs where you find the LibAddonMenu-2.0, and other librraies, in subfolders, and IF there is NO txt file of the library as well like <libraryName>.txt (e.g. LibAddonMenu-2.0.txt) to include the librarioes FULLY with their txt files!!!
Provide them this link:
https://wiki.esoui.com/Libraries#Providing_libraries_.28standalone_.2F_bundled_with_addon.2C_but_how.3F.29

Wrong:
users/docuemnts/elder scrolls online/live/AddOns/AddonName/libs/LibAddonMenu-2.0/LibAddonMenu-2.0.lua
users/docuemnts/elder scrolls online/live/AddOns/AddonName/libs/LibAddonMenu-2.0/LibAddonMenu-2.0/controls/...

Correct:
users/docuemnts/elder scrolls online/live/AddOns/AddonName/libs/LibAddonMenu-2.0/LibAddonMenu-2.0.txt
users/docuemnts/elder scrolls online/live/AddOns/AddonName/libs/LibAddonMenu-2.0/LibAddonMenu-2.0.lua
users/docuemnts/elder scrolls online/live/AddOns/AddonName/libs/LibAddonMenu-2.0/LibAddonMenu-2.0/controls/...

This applies to ALL librraies which got their own txt file. They need to be included WITH them so the addon manaegr finds them properly:
https://www.esoui.com/forums/showthread.php?t=9149


Or they should not be included and just installed "standalone" directly to your live/AddOns/ folder, like a normal addon (also with their txt file, for sure!).