Unable to add device to account

Hello, I am trying and unable to add a device to my account as a managed device.

TeamViewer on the remote device is run from a non-admin account so it won't let me add it to the account. It says "to set up unattended access, you need administrative rights". If I try to start TeamViewer on the remote device with admin rights (still from the non-admin account, I don't have a choice), I can't sign in. It says something like "Microsoft Edge cannot write to its data directory" (I use single sign on method).

So my next step was to try to add it remotely, but it asks me for the "personal password" for the device. I have no idea what password it's referring to. I have tried my TeamViewer password, the Windows password associated with the (non-admin) user account on the remote device, my single sign on password, the TeamViewer password for the remote session, none of them worked.

So I'm stuck. Can anybody help?