Install Mobile Locker in Classic Outlook
You can start here if you need help deciding which Outlook you have. Below is the step-by-step guide on how to install Mobile Locker in Classic Outlook.
Open Microsoft Outlook and go to your Inbox. Click the More Apps button in the sidebar or All Apps in the ribbon.
Click Add Apps.
Search for Mobile Locker, then click Mobile Locker for Outlook.
Click Add.
After it installs, close Outlook by closing all of its windows. It would be best to close all Outlook windows, or it will not work correctly.
Reopen Outlook.