Solution
Setting up OAuth for Lexmark Google Apps
Open the printer’s Embedded Web Server (EWS).
Set up FAC. To do so, configure a security template that can be used by the app.
Go to Settings – Security – Security Setup.
Configure a Building Block (e.g., Internal Accounts).
Configure a Security Template that uses the previously configured Building Block.
Go to Settings – Security – Security Setup – Access Controls – Device Apps, select App 1 or App 2 (depending on what you will assign in the app), and then choose the previously configured Security Template.
Enable OAuth in the app. To do so:
Go to Settings – (Apps > App Management) or (Device Solutions > Solutions (eSF) – Google Cloud Print – Login Settings – Function Access Control.
Set the FAC in Login Settings to the one that corresponds to the Access Control set in Step 1.
What to expect for first time users
During the first login, establish a token that will link device credentials (e.g., Internal Account) with your Google account. This only happens during the first login.
Go to the printer and tap the Google Cloud Print icon on the control panel to launch the app.
Click E-mail for the app to send an automated email with the code.
Click on the e-mail link (i.e., https://www.google.com/device), log in to your account, and then register the printer using the code.
Enter the code, click Continue, and then click Accept to confirm authorization. The app should be now ready.