Are you sure that is the number for the JuliaCon registration? Many people have successfully used this flow this morning. But someone else found that using a registration number from another event causes a “internal server error”.
Is that the case, maybe? There may be other issues, of course, but I thought it’s useful to verify.
I tried my number (without #), it seemed to work, but then the process hangs at ‘juliacon-bot wants to access your account’. Neither Authorize nor Cancel do anything.