Brake weirdness on my new E-bike
You seem to have tested the rear wheel. Have you tested whether the front wheel and brake are making the noise? 

Also are you pulling the correct lever to operate the rear brake? It depends which country the bike was built in as to which one operates the rear brake. So in the UK the left hand lever operates the rear brake but in the rest of Europe (I believe)its the right hand lever. If you are pulling the front brake lever then obviously the rear wheel will not stop spinning. With the bike on the ground pulling either brake lever will stop the bike moving.

Ticking can be the rotor disc very slightly touching one of the pad. It can be a tick once-per-rotation of the disc if the disc is slightly warped at one point. The ticking would stop when the brake was pulled on as the pads would fully engage and make other louder noises.