I share a contacts folder with a fellow team member at work and, instead of
using the open notes field in each contact, I started R clicking on emails &
in-cell edited notes from the email screen & assigning them to a specific
contact in that folder.

Those emails & notes are then kept in a reference folder of mine. The
problem is when I open a specific contact and click on the activities tab all
of the emails & notes show but when he does the same thing nothing shows.
The permission levels are at 'owner' for both of us on the contacts folder
and the reference folder where all the emails & notes are kept. I noticed
that when I R click on the contacts folder on his computer the activities tab
(for set up) is not there at all.

How can I fix this so he sees & has access to the emails & notes in the
reference folder when he clicks on the activities tab in any contact? Thanks.