To give a user the Page Manager role:

1) Navigate to Core.
2) Select Users/Access > Profile > Edit User Profile Data.
3) Search/select your user.
4) Scroll to the lower left of the user's profile under System Information, and select Role Membership.
5) Click Edit in the upper right corner.
6) Locate and select Page Manager, then Save.
7) The user will need to log out/back in to see the changes.