Accessing NextCloud 20 with older iOS devices? There is no iOS app and the browser doesn't show the login screen

Have any of you ever been able to solve this issue?
iPh5s & iPad Gen4 in an intranet, without any WAN.

I put the iOS provisioning link for CAL and Contacts on a local https-website, then use Safari to browse to:
https://nc-some-intra/remote.php/dav/provisioning/apple-provisioning.mobileconfig

At least this part works well.