I just managed to get Anbennar working, and I mostly followed the official installation guide video:
https://www.youtube.com/watch?v=xtnJlra-NyI I did not, however, grab the current state from gitlab, but instead used
https://www.steamdb.com/en/tools/steam-workshop-downloader and steamcmd to download the current Steam Workshop version of the mod (
https://steamcommunity.com/sharedfiles/filedetails/?id=1385440355). That's just because I want a "stable" mod version instead of the current development state.
Then I copied the mod into the folder you mentioned. In my case it's different, because I am on Linux: "/home/<name>/.local/share/Paradox Interactive/Europa Universalis IV GOG/mod/" and renamed its folder to "Anbennar". After that I modified the mod's .mod file to contain the "path" entry mentioned in the video, and put it directly into the "/home/<name>/.local/share/Paradox Interactive/Europa Universalis IV GOG/mod/" folder.
After that: Enabled in the Launcher and Profit.
I'll attach a screenshot that hopefully makes my final setup clear.