Smartthings Integration Issue - Unable to setup the smartapp. Please try it again

My system is like below;
Intel NUC 11 - HA - ST station - iphone - ST app

(all the s/w, f/w versions are the newest)

I have been trying to integrate my smartthings to HA.

I use Nabu Casa to activate HA cloud and it works fine. >> url starts from https, instead of http

Also, I made my smartthings access token properly.

But when I try to integrate ST to HA, the error message (Unable to setup the smartapp. Please try it again) keeps on.

Please help me to work this out. This makes me crazyyyyy…