To be able to use Fast Travel you must first unlock the Illapa Project mission in Wachikuni. To do this you must complete the Wanay Extraction mission which involves freeing and escorting civilians to join your rebel cause. Upon completing the Illapa Project mission you will have access to your first pilot which now allow you to click any point of interest or location on the map and request transport. You will not be able to Fast Travel at will as the pilot will need to refuel after each action which means they will be unavailable for a short period.