If you see the Log In screen, type your username and password into the blanks and click Log In.
 Use the search box at the top of the screen to navigate to the desired group., It’s the green button just below the group’s cover image. Once your request is approved, you’ll be notified that you’ve become a member.

Some groups allow any current group member to approve incoming join requests, while others only allow admins to do so.
Open https://www.facebook.com in a web browser.
Go to the group you want to join.
Click Join Group.
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