Once you are added as a user in Target you need to have the Approver role in order to create Activities. The Admin of your account can make you the Approver. If you are the Admin then you can give yourself the Approver role from Setup > Users under Target Standard.
I added a new user to our Default Workspace, and have set their Product Role to Approver. They also have Product Administrator access. However they are not able to log in, and, when attempting to log on they are only seeing the Target Classic option.
bkmills1 Without having more details about the orgid and username it is a bit difficult to diagnose what the issue could be. Hence I would recommend that you submit a support incident with customer care and we can help you with the same.