On a paper that I have it says that if the lounge is closed, show a crew member your gm Id and you can gain special access to Test Track without waiting in line.
I have a friend (a GM employee) who was there last week. She told me the lounge was closed, but is supposed to open by the end of the month. Not sure if that will happen, but it won't be too much longer.
I kept my badge when I retired but it's the same one I use to show before retirement. GM use to give out the golden badges to retires DH has one. They quit giving those out before I retired.
If you don't have a badge maybe call Disney and find out what you would need. If you find out please pass along the info in case I lose my badge.
The latest ticket order form says retirees can print an ID from the retiree website or present a pension stub with financial info blacked out. I would assume the requirements would be the same to get in the lounge