I installed a Amcrest NVR system and 4mp Doorbell camera. It's working with the amcrest home view app but when he tries to pay for a cloud account on the Doorbell it says the SN isn't long enough.
Do you still have the box it came in...? The serial number label on the box might have some longer extra digits. The Lorex doorbell camera uses a QR code for setup and there are no fees, plus they have great customer support.