welll, Theres three different versions of that. The Game Pass version, the Microsoft store version and the Steam Version.
The Game Pass version ( the 1 dollar standard and the upgrades ) wants you too install things in C:\Users\warch\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\Packages\Community and nowhere else. It also wont recognize .mdl files.
The Microsoft store version wants you to install things in (install drive ):\( Install Directory )\Community, but does recognize .mdl files when ported correctly.
Ive got no clue what Steam wants.
Placing your addons anywhere else other than the specific locations I have listed above will result in problems.. There are as many as three Community folders on your drive. One is in app data, the next is in the install drive and install directory and the third is in wpsystem. two of those are hard linked to the third, which is the main community folder. FS2020 knows which are links and which one is the main folder for that specific version. Thats why its very important to only install addons to the correct community folder..