Old RPC to UNet (Server to single client)

I have a client project and a server project, and I currently am using the old RPC method. I'm trying to convert this code to UNet, but I'm not sure how to begin since the code is different on client and server. I do not want database information client-side. Can anyone give me some pointers on how to achieve this with UNet?


The client starts the RPC with RPCClientAuthenticateGet with their username and password.

Client
Old RPC to UNet (Server to single client)