Are you trying to sign in to Roon or Roon ARC? You can’t sign into Roon unless you are located where your Roon server is located and on the same local network.
If you are trying to sign in to Roon ARC, have you got it properly set up on your Roon server and router with port forwarding?
If you are trying to sign in on the store’s Roon server, you need to be set up with a profile and password and be on the same network.
You haven’t provided enough information for anyone to be able to help you.