For anyone who struggles to get into their Ubiquity CloudKey Gen2 via SSH… There are a bunch of forum posts swarming around offering a wide variety of options. ubnt/ubnt, root/ubnt… For me, using version “UniFi OS UCK G2 Plus 3.1.9” the following combination worked:
Setup the SSH password in the CloudKey:
Now you could use the username root and the password you just setup to SSH into your CloudKey: