Nextcloud stucks at grant access

Hi guys, I have installed nextcloudpi on my omv machine followed this link:
It is installed on a AMD machine inside docker not on RPi. And I don’t have any proxy settings. All the apps and servers are latest as of 03/13/2020

However, after I set everything up and try to access from iPhone. It stucks at grant access after I input server address, username and password. Also I have added the "overwriteprotocol " to https but it doesn’t work.
I also use duckdns for a external access. But I tried both in the Wifi network and external access but neither work.
So could anyone please help me with this?
Thanks a lot!

Try on a browser first, can you see the login page? Are you able to login via https from anywhere

“Does not work” is not very precise, can’t you resolve the dns name, does it just not establish a connection, does it connect but not authenticate?