The Swissport lounge at ORD is open for like 2hrs a day to PP members at best, it’s also a terrible lounge where spending time in the terminal is better. Also you are going to be most likely flying out of Terminal 3 on AA anyway. Only good way to t5 requires you to exit security and take the train and re-enter the secure area which you wouldn’t be able to do without a T5 boarding pass. There might be a secure side bus but it’s not worth it.