Need help setting up public keys for SFTP/SCP server

We just spun up a Windows Server 2008 R2 server (VM) and installed SolarWinds SFTP/SCP Server.  That's set up fine and I can sftp files from the Unix box.

We now need to set this up so that a job can be run on the Unix box and sftp the output file to the windows box without needing a password.  That would require public keys set up.  Question is, how do I set up the key(s) needed?  I can not find any documentation about this so any help would be greatly appreciated.

Thanks.