Configuring preferences and options in Outlook.com
I am having the same issue with the "Unable to load these settings. Please try again later." under the Sync Email settings. So I followed the instructions above, eventually just decided to sign up for the Microsoft 365 Subscription, and yet I continue to get this error message and cannot sync one of my Gmail accounts.
I am continually getting emails every day that tell me I need to "Update the credentials" for that Gmail mailbox, and yet there is no way to do so because the Sync Email settings do not work.
Also, the link Add your other email accounts to Outlook.com (microsoft.com) **** is extremely unhelpful and useless because it directs you to a separate page that has limited information and where you are then directed to "Add Account", which just takes you back to your main Outlook mailbox and nothing else.