Oculus Quest: "ERROR: You uploaded a build for platform Quest but the app's platform is Mobile"

I've been scratching my head with this one for days now. What I initially wanted to do was to deploy an existing VR project (Oculus Rift) to Quest. When I upload the apk using the oculus platform tool I get the error described in the title. I tried reinstalling Unity, I tried using different computers, all with the same resutls. Then I started from scratch with an empty project, import OVRUtilities, add the default sample scene to a build, and build. I still get the same error when I try to deploy. I did create an app key and an app secret and set those in the platform settings and platform tool prior to build/upload.

What puzzles me the most is that the 'start with an empty project and see if that works' worked once, on one machine, but I can't get the same process to work on another machine. I've been searching online to see which of the Android related player/build settings might cause the apk to be compiled for mobile instead of quest, but obviously didn't find anything. After logging in to my oculus developer account, I tried creating an app targeting Oculus Rift and use those credentials, and creating one targeting Oculus Go/GearVR (mobile) and use those, but no dice. (using Oculus Go/GearVR as the target platform in the platform utility just leads to errors related to the manifest not being configured correctly). Has anyone else here seen this before? Any thoughts on what I am doing wrong (and why I can't get a 'hello world' empty project deployed to a Quest 'just' by selecting 'Android' as the build platform in Unity)?