Early in the game, you can only fast-travel anywhere in the map back to your homebase, Prosperity and liberated Outposts. You should upgrade your Expeditions facility to LV2 to be able to fast-travel to any discovered location in the map.
After further upgrading your Expeditions facility to LV3, you'll be able to have an option to fast-travel and get dropped from the air. This is somewhat useful especially if you have the Wingsuit ability unlocked. From the air, deploy your wingsuit and it will allow you to travel faster. This is recommended if you want to reach a nearby location that you can't fast-travel to yet.
There's no payment or resources consumed when fast-traveling so use it as much as you want to move around the county.
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