Cannot fetch themes - error 500

Using directions from my hosting provider, Krystal (Node.js App setup guide - Krystal Hosting Knowledge Base), I’ve managed to install Ghost on my CloudLinux 8 shared server with SQLite3 DB. It almost works. Ghost doctor says there are no issues, but when I try to install a new theme from the admin panel I get the error “, cannot fetch themes” at the top of the page in red.

In the console there’s an error 500 listed on the URL;

I get the following error;

{"errors":[{"message":"Resource not found","context":null,"type":"NotFoundError","details":null,"property":null,"help":null,"code":null,"id":"d04a8aa0-b9fb-11ee-8da3-211042466373","ghostErrorCode":null}]}

The Ghost install seems to work OK other than this and I can upload themes OK. Should I ingore this issue or does anyone have any tips?