In order to add people to be able to edit first add them using Space Tools in lower-left corner.
In the drop-down select Permissions.
Then select edit Permissions.
...
Put their UVA email in to send an invitation to edit.
Note: If you are an admin (or recently got permissions) and if you don't have edit privileges on any of the sub-pages, then navigate to that page > click on the "pad-lock" sign / three-dots on upper menu bar > on "Restrictions" page, add your-self like in the previous line.