Remember that Microsoft is recommending users to go for Azure AD B2C instead of local authentication
have you already defined Web Page Access Control for you pages? those can be set by Web Role, so this would fit your requirement
can the users still login when they are not approved? if yes I guess there is nothing you need to do.. your approval process will give the privileges to the additional pages once approved
if they cannot login, I suggest playing with the flags "login/lockout enabled" can't remember which one, but one of those would lock the user
------------
If you like this post, give a Thumbs up. Where it solved your request, Mark it as a Solution to enable other users find it.