If you are unable to select a location on an intake form, it likely means one of two things:
1) You've selected "Foster" for the Intake Into field, thus you do not need to select a Location because the animal's location will be the Foster Parent that you select. Your intake form should be submitted without a location (you will not be able to select a location).
2) If you've selected "Shelter" for the Intake Into field and you cannot add a Location, this likely means you do not have any locations configured yet. To add an animal to a location other than a foster parent, you'll need to first enter the location into your configurations (just navigate to Configuration > General Shelter > Location Management). This list may include shelter location(s), vet offices, boarding facilities, pet stores, etc. (see Adding/editing shelter locations).