Hey, I also had this problem and did fix it for myself.
So I ended up making a dummy txt. (as Jwaker4258 suggested) and made a new error. After some looking, the error code I got (Errrno 13) is a python error, its caused by a lack of permission to view a file that doesn't really exist. Then I used a "chown" function within [(the file where the mod loader is stored)/pluggins/basic_games/basicgame.py] and manually applied the code. (see attachment 1)
With the assumption that the attached images are unclear, first make a txt. file within the subnautica game folder labled "doorstop_config.ini" (I also made a second version as a folder with the same doorstop txt. file inside of that for redundancy sake). This is the file that the error is searching for. (see attachment 2)
Make sure to write the code in above the "def" functions and below the "import" and "from" functions to ensure it works properly. Enter the line "chown user:(your user stored on computer)" in the basic_games.py file and save it temporarily (I kept the txt file open to delete this line after everything was working properly).
After doing so try opening MO2 again and hopefully there will be some jank about MO2 not being able to work with subnautica and then give another error (I unfortunately didn't get any screenshots of this). Then open up the Software one last time and it should give an error about the chown line and still open right up to the MO2 UI. If all goes well the chown line should be safe to delete.
After everything was fixed I immediately deleted the instance from MO2 and currently don't have any problems with it. I really hopes this helps anyone who needs it.
