When running a command like this:
cloudflared tunnel run --token <base64-encoded-token>
the base64-encoded token is a json file with a, t, and s fields. This json file however cannot be used as a credentials file. If you decode it, put it in a file, and then put a line saying "credentials-file: /path/to/cred.json" and run `cloudflared tunnel run`, you'll get errors lie:
2022-10-23T22:26:56Z ERR Failed to serve quic connection error="Unauthorized: Failed to get tunnel" connIndex=0 ip=198.41.200.33
2022-10-23T22:26:56Z ERR Register tunnel error from server side error="Unauthorized: Failed to get tunnel" connIndex=0 ip=198.41.200.33
The cred.json file needs the same three values as the base64-token, but they should be named AccountTag, TunnelID, and TunnelSecret.