Apart from Dokku, there's coolify and caprover.

Happens to the best of us! localhost or 127.0.0.1 should work too.

Did you get it to work?

Cloudflare tunnel only requires outbound port opened, check if you've allowed all outbound ports in EC2 security group (the default VPC should have this already).

Otherwise it's probably a misconfiguration reaching the IP/port of the cloudflared service on the EC2. Have you tried checking cloudflared logs? Does your tunnel status show up as healthy?

Just FYI, your account shows up as a bot. You should change it in your account settings.