Check50 has passed all checks for pset6 except for the request of test.css and test.js. But these files do not exist within the pset6 folder, so how should this work? I tried requesting each of the with the cs50 server and it also did not work. Am i forgetting about something, or is it impossible to pass this check?
It's hard to say if you're forgetting something, but rest assured it is possible to pass this check. The auto-grader will give the same result as the check50s, so if you do not pass all the tests, it will be reflected in the grading.
When you requested them with server did you got a "404 Not Found"? If so, then technically it did work, since those files do not exist. If not, that's a good starting point for your troubleshooting.
All things being equal, this seems to indicate a problem in your lookup function. You could test it by adding a test.css file to your public folder. It doesn't have to be a "real" css file, perhaps copy hello.html to test.css. Then request it in your browser or curl to see the result, and to see what feedback server gives.