Is the game pass version only meant to be the standard version or is it Premium. I thought it was the bog standard version but I have all 30 aircraft and high detailed KSFO and EGLL.
I have the game pass too, but i dont have the premium content… I think you went out of luck! 
Did you purchase the upgrade? As I understand it from reading other posts, if you have Game Pass and purchase the upgrade then you get the extra aircraft and airports. If you decide to cancel Game Pass then the upgrade is worthless until you purchase the base game again.
I have Game Pass with all the standard aircraft. I am considering purchasing the full standard game this month now that Game Pass is out of beta and the price has gone up.
No, the only thing purchased was game pass ultimate.