It wasn't opened last time I checked, but can't remember exactly when that was...sometime last month I think. I used to check everytime I went through but gave up as even the TG workers say they have no idea anymore when it will open nor why TG management hasn't opened it yet as it's been completed for at least 5 or 6 months now.

It is supposedly only for business or first class passengers on TG, but I think any TG flight will do, whether domestic, short-haul international, or long-haul international. As long as you have your boarding pass showing you just arrived on TG in C or F it should get you in. Any ROP or other *A Gold cards won't make any difference. That's my interpretation of what TG has announced about the lounge, but don't know if it will be implemented exactly that way or not when it opens.

The lounge is located after you exit customs, all the way to the right, just beyond exit A and the TG baggage handling room.

If you ask TG staff about it and they say it still isn't opened, they may offer to allow you to use the appropriate C or F departure lounge airside. When I asked once about it they offered that to me, but I declined. If you don't see any TG staff at the gate to ask, just go to the airside lounge and try your luck there, while complaining that you were expecting to use the arrival lounge but it isn't open yet.