The website is not secure. It is using https but no valid certificate.
When I tried this with chrome from my home computer I got a certificate error due to HSTS I then opened edge and did a two system verification and was able to sign in with Chrome.
So either it was an verification issue or fixed while I was working or I was lucky.
Try it and if you still have an issue please notify the Seller portal 1:1 and I’ll notify them internally as well.
Samsung Developer Program