Can't run LE 11 trial on Mac

Hi, I own Cubase LE elemants 10 on Windows, and I now want to try the Cubase LE AI 11 demo on my new Mac. Steinberg sent me a code via email.
When I enter the 11 licence, it says it’s a Elements 10 licence and that already been used !!!
But this is NOT 10!!! Can I not install products on different computers? And why is the version messed up like that.
Do I have to buy another licence dongle for the Mac?
edit I also bought 7 for the Mac years ago, but I can’t install it as Apple says Steinberg’s 'Developer ID" license had expired in 2017. What the heck is going on?