Authenticator Pro can generate the 5 character codes used by Steam. However, it does not support confirming trades.
Option 1 (advanced)
Set up an account using steamguard-cli and export to a QR code.
Option 2 (Windows only)
The procedure is as follows:
- Set up a new authenticator using Steam Desktop Authenticator (SDA). This will handle the conversion of the Steam protocol to a standard
otpauth://URI. Do not enable encryption just yet.
- Once up and running, in the directory where you are running SDA, you will find a
maFilesdirectory. This contains your account secrets.
- Open the file for your account called
STEAM_IDis the unique identifier for your Steam account, using a text editor. If you are setting this up for the first time, there should only be one file.
- Find the
urijson property it will have a URI in this format
- Create a QR code using this string with the QR code generator, or enter the secret part of the URI in Authenticator Pro using the Steam type.
- (Optional) Enable encryption in SDA. You should keep using SDA because it's the only way for you to accept trades.