Issues creating new experiment on Pavlovia

Description of the problem:
I’m having some issues pushing my experiment from the builder onto Pavlovia itself. While it does show up under experiments, I cannot actually run it as a pilot from Pavlovia as I get a 403: Forbidden window whenever I try. Additionally, when I try to create a new project with the experiment I get an upload error! Image attached of the error. image|683x288

Edit: I also get an error when I try to “run online with Pavlovia”:

Further edit: Not sure why the first picture shows as a hyperlink, and the second image just pasted into the post.
Really not sure what’s going wrong, I’ve tried to reinstall psychopy, move the folder around, made sure there are no superflous files within the folder etc.

Many thanks,