Cannot create new file in public directory (error 500)

I tried cloning the repository and running with Docker. I wanted to make an account and do a simple test by creating "test.ttl" under my public directory. However, nearly everything I tried was greeted by an error. Here's my adventure in trying to do so:

1. Created a new account
2. Log in
3. Navigate to /public and create new source file with "+" button
   Result:
   
4. Try to escape by pushing the home icon
   
5. Log out and try to log back in again
   
6. Eventually manage to log back in. Go back to /public, am greeted by unexpected looking page:
   

Docker logs say nothing. There's a lot of errors here without much helpful output, so I don't really know how to go about figuring this out.