This can happen if your security permissions restrict you from accessing the Projects screen. You need to make sure that you have the proper security permissions that are compatible with your assigned subscription package. For example, if you are subscribed to the Manager and Time & Expense packages, you should not set the security profile of the user to Time and Expense Only because it would restrict you from accessing the screens other than the time and expense screens.
You can set the security profile for a user from the Settings > Security Permissions > Actions > Assign Profile. You can also customize the security profile for the user as per your needs. Check Core Help Center for details.