group membership approval workflow request question

I am trying to setup the approval by primary owner workflow for group membership change. However, it didn't seem to work and I am hoping to get some help here. This is a new AR 7.4.3 setup without too much customization. 

What I did

Defined the primary manager for the group which I want users to be able to initiate the change request.

Checked the "Approval by the primary owner (manager) of the group" option under the Membership Approval tab in the group's properties.

Enable the  "Approval by Primary Owner (Manager)" workflow (enabled by default)

What I see

When a regular user login to the AR helpdesk portal, the Add button is not available under the membership option. Users are unable to initiate the request.

When the ARadmin login to the AR helpdesk portal, the Add button is available. However, the admin can add (ARadmin is not the manager of the group) user to the group without being prompted for the approval.

I think I am probably missing something for the regular users. Do I need to give them write permission to the group first? I would assume that is no need since it is going through the approval process.

Thanks