I can't add a payment methods

I have tried to add payment methods many times, but this is the error every time.

Which method are you trying to use? That 404 screen doesn’t look like a good sign.

If you’re still having trouble, open a Support Ticket (and let them know about that 404 screen also).
Login to Cloudflare and then contact Cloudflare Support

Use Chrome instead. Can not edit it on Firefox.