Seems I am unable to figure out how to cache maps on the herelink so when we are onsite we can have maps on the controller while not internet connected?
Are you using Solex or QGC?
For QGC, check their instruction:
https://docs.qgroundcontrol.com/master/en/SettingsView/OfflineMaps.html
For Solex, it uses MapBox, which means it loads maps when there is internet. Pre-loaded area will be available when offline.