There are a few settings you can check on your phone that might be causing problems during the authentication process.
What to do next?
- Check your Safari settings. Go to Settings → Safari and look for "Prevent Cross-Site Tracking" and "Block All Cookies". Disable them and try again.
- Disable any Content Blockers that may be active on your Safari and try again. Go to Settings → Safari → Content Blockers:
- Make sure you're not using incognito/private mode on your browser as this might also affect the process.