We had something similar the other day using a MS Surface to a monitor. My colleague couldn’t get it to output using his mac display port adapter. We tried with my startech one and it worked first time as you’d expect. Once the surface and monitor had worked using my adapter they then worked with his adapter which was rather strange.
We do this for a living so we’re fairly sure it wasn’t user error but you never know.
I’d suggest you try to connect to a monitor or some other screen to see if you can get an output to that. Also try to set PowerPoint in presenter view to see if that has any effect. I think at the moment your mac isn’t seeing the projector but it may well see another device – once it’s done that hopefully it’ll see the projector.
Many years ago you couldn’t get Sony laptops to see Sony projectors because the eprom chips in the projectors wouldn’t talk to the laptops properly and you’d need to put a dummy load on the laptop to adjust your settings before connecting to the projector.