Click on "Site Settings" and then on the next page you're looking for "Insecure Content" as seen below:
Set that to Allow. Reload the site.
It's not great, and there is an effort to make changes to the site, at long last, which should help avoid creating a problematic security exception to using the site.
Download Chrome or Firefox and do the same thing . I have to imagine you can adjust site settings in Safari on iOS. But given that I don't have an iOS device, I don't know how that is done