Does it not have a power cable with an audio jack built in? Garmin tout this model a suitable for bike/scooter use. Maybe this is an accessory (not shown on the Garmin website though as I've looked).
Not really a problem if you're using it to replace an existing sat nav but for a new user, yes.
The cradle for the Nuvi 550 was £8 and the Power Q cable £30
theres a Wanted/For sale section that you can use 


if it was I’d get rid of them and ask the guys at the Zumo forum, here (and me).