If there isn’t a text file then the issue isn’t creating the datapack, in which case you need to first re-install your server then go through the steps in order.
I have a feeling your server is missing files from the recent update (cfg/nosend.txt and cfg/bootstrap.txt) as well as some base gamemode files that have changed. So I suggest you follow these two steps to ensure your server is completely up to date:
- delete the orangebox folder.
- (After completing step 1) Run hldsupdatetool to download gmod.