Once user is registered in Aha!, they should be able to easily see what they have access to

We don't provide access to the Aha! portal to our customers. Customers are only provided access to our roadmaps through Notebooks. When I add a customer as a user on Aha! and provide them access to a pseudo product which has access to the roadmap notebooks, the customer receives an invite and registers himself/herself. However, once registered, the user is taken to the generic Aha! portal where he/she tries to access various parts of the portal but since I have not given them access, they get confused and don't know where to go. I then get these as complaints from the customers and that too only if they complain. Some customers just quietly assume that we have not provided them enough information. It defeats the purpose of sharing the notebooks with them. We need to be able to customize their welcome screen to Aha! so that they immediately see what they have access to instead of seeing all the standard parts of Aha!.