Step 1: Configure your Gmail account for IMAP

1. Sign in to your Gmail account.
2. Once youre logged in, click the Settings icon in the top-right corner.
3. Click Settings.
4. On the Settings page, click the Forwarding and POP/IMAP tab.
5. From the IMAP Access section, choose Enable IMAP, and then click Save Changes.

Step 2 Add an IMAP-enabled Gmail account into Outlook for Mac.

1. Open your Outlook for Mac application, and click Outlook >Preferences >Accounts.
2. In the Accounts window, click the plus (+) sign in the lower-left corner, and then select New Account.
3. When prompted, enter your Gmail account e-mail address and password.
4. Now, click Allow.
5. In the dialog box that appears, select Open Microsoft Outlook.
6. Click Done to start using Gmail in Outlook for Mac

This May Help,
Peter