Cannot register nuvi65

Have just purchased a new nuvi65 lmt and have tried to register it to update maps. Have imac (late 2009), loaded OSX yosemite V10.10.3 and Garmin Express. When I connect nuvi65 and try to register, Garmin Express connects to the nuvi, and when I try to register the screen allows me to insert my email address, allows me to select 'Offers and Promotions' (button inserts tick and changes color), but trying to click on 'nickname' or 'register' does not have any response and does not allow me to continue - I can only back out of the screen. Can anyone offer advice? (I live in Australia).