Transmission giving a 403 (forbidden) error

I'm trying to add the torrent widget, and set up an app with Transmission. I gave it http://IP:PORT in both the internal and external addresses, and gave it the proper credentials. The Transmission daemon is running on the same PC as Homarr (not in a Docker container), and other integrations like Jellyfin and Sonarr work correctly. The torrent widget does not work.

Solution