If the user is created, linked with a Salesforce user, and added to the Manage Licenses list, but still cannot access the TimeTracker app. You need to check the Permission Sets to ensure the user has access to the required objects.
Steps to follow:
Create a new permission set for TimeTracker if it hasn’t been created yet. Follow the instructions here.
If the permission set already exists, make sure the user is assigned to it. Click here to learn how.
Verifying and assigning the correct permission set should resolve the access issue.