When my son was born I went to add his birth cert and SSN. I couldn’t. The “attach file” button is still there but it simply doesn’t work any more.
After hours of troubleshooting I finally found a discussion on their own support form where they acknowledged they explicitly disabled this feature. The solution is to switch to a paid subscription.
I’ll never buy software from them again. That’s just one example. They’ve removed similar functionality from cloud sync services to compel users to buy a subscription.