Hey there, vern130!
Thanks for reaching out in Apple Support Communities! If we understand correctly, you receive an error regarding the webpage being secure, and when you try to submit to open the page it goes back to a login screen. Let's see if we can get your pages working smoothly!
First, have you tried to clear the browsing history from Safari, then opened the page again? If not, give this a try to see if there was something in the history or cache preventing this page from opening:
Clear the history and cookies from Safari on your iPhone, iPad, or iPod touch - Apple Support
Should this error reappear, use the information from the following support article to help understand the alert being seen:
If you see a "Not Secure" warning while browsing the web with Safari - Apple Support
As mentioned in the above resource, try reaching out to the site owner or admin to find out what's going on with the security of the website.
Warm wishes!