After logging into EXPA you are getting redirected to the Opportunity Portal?
The requirement for accessing EXPA is a team position with corresponding starting and end time.
If you get redirected to the Opportunity Portal this means that you are not assigned to a team position yet or that the duration of your previous position expired.
Kindly ask a Team Leader or EB to assign you to a position with a corresponding starting and end time.
For more knowledge about team member positions please check out our article center :D