By marking a port untrusted, you are saying you want to identify the device. This enables a AAA profile, with a role, thus the visibility of the client on the user table. If you mark it trusted, then all traffic is allowed, no identification/authentication necessary.
Your assessment of your workstation on port 1 is correct, thus the :0/1
However, I am not sure what 255/9 is. I just tried it on a RAP-3 and it shows up as 192.168.3.230:0/2. Not sure where you are getting the 255/9 from.