Is there a way to use Group Policy to add a user to a security group when they are dropped in an OU that the policy is linked to? Or is there a way to assign NTFS permissions to an AD OU? The end ...

Use "sudo usermod -a -G example_group example_user" to add a user to a group. To add a user to multiple groups at once, separate groups by commas, like "sudo usermod -a -G group1,group2,group3 example ...