Google Auth on Windows Desktop

We strongly advise you to use one of the options on a mobile device, using the same desktop for GA as your using to login defeats much of the point of using MFA.  This allows compromising 1 device to compromise both credentials. 

However if you don't have a mobile device there are several options that will work.

There are Browser plugins for Chrome and Firefox that will generate GA codes. Here is 1 example

Authenticator.cc has plugins for Chrome, Firefox, and Edge.

Authy is available for Windows.

WinOTP will also generate codes.