I created a usergroup and gave it a permissions for frontend event editing. When the user creates/edits an event from the frontend, the list of locations don't show in the location dropdown, even if the usergroup has been provided with frontend locations creation permissions.
By default, the system will only show locations created by himself. If you want to allow showing all locations in the system, go to Events Booking -> Configuration, set Show All Locations in frontend event submission form config option to Yes
After that, he should see all available locations in the system