Yes, you need to have clear signal to the Satellite.
In underground parking garages, or tunnels you will lose the signal. (but that happens in all other cars as well)

Harley includes a bracket to mount the antenna under the fairing next to the radio.
If you take off your outer fairing, you will notice the GPS antenna mounted the same way.

But a lot of users choose to mount the antenna outside the fairing.

This picture isn't mine, but mine is mounted very similar.
Works very well here.