@Capt_Bucky_OHare unfortunately that path is currently hardcoded into the game as the original supcom fa data folders are placed into your documents folder. There is some work to make that not the case in the future but at the moment it uses the documents. The other option you could try may be to turn on the vault fallback location in the client settings as that will use the program data folder but fa itself will still look for the documents folder.
Thanks a lot guys!
Should have looked here before closer, but I am just not enough into coding or have not read it through well enough, so that I got it where the mistake was coming from...
If you installed the client with admin privileges then it wont be able to access the files as a normal user. You would need to reinstall it as a normal user.