Very interesting that you run NCS on Raspberry pi3! Users are interested in that, but I have never seen any results how it works. If you have the time to just write something about how many cameras, resolution, motion detection etc. it is very much appreciated.
Login to NCS without any credentials, no username and no password, it not possible due to security. There are Tokens involved in this also so need some assistance from @Steve to give you a correct answer.