Mullvad - "TAP-Win32 adapter missing"

I'm trying to trial Mullvad VPN. After installing it I'm getting the error message:

"The TAP-Win32 virtual network adapter is missing. Restore it by running the installation program again (Quit the program first)."

Running the install again didn't fix the problem. I gather I can get this adapter by downloading & installing the Open VPN client, but I'm not sure if that could cause problems. Shouldn't this adapter be part of the Mullvad installation? It's not being sandboxed or anything either. I'm afraid that maybe the OpenVPN client I download may not be compatible with Mullvad (wrong version or something), and don't want to brick my PC here.

I'd appreciate any insight.

 

Fixed the problem by uninstalling, installing the adapter via the OpenVPN client first, then re-installing Mullvad.

Only to run into another problem: My trial subscription for Mullvad has somehow expired event though I haven't used it yet. Well, that was my quickest trial ever.