Same. No portal if you are not leaving the airport.

After landing in SJU, you will do immigration, baggage claim, and customs as normal. They after you go up the the baggage level from customs, the national guard will be there blocking the elevators to go upstairs to the counters and security area. You just show you connecting flight info and they allow you access to the elevator. You will go up and recheck bags if necessary and clear security as normal.