Check permissions on the UserInfo entity. When you make specializations, permissions do not propagate from the generalization.
Also, in the microflow above, you are creating an Account object, not a UserInfo object. But in the page, you show UserInfo. I think you should be creating a UserInfo object.
Lastly, because you are creating a specialization from the Account object, the security rules regarding user management apply. In the App Explorer, open the Security page and click on the User Roles tab. When you open each User Role, you will see management permissions for each user role.
Hope that helps,
You may find it easier to create a new entity with a 1-1 association to Administration.Account to hold your new fields.
This is the approach I take when looking to hold extra data associated to an account holder.