You can use Remote on your Start9 device using either Tor Browser or by using a standard browser on your LAN.
When using Tor Browser, go to Remote->Interfaces and copy the Tor Address. Paste this into Tor Browser and bookmark it. Remote should load. Next you will want to provide Remote with the connection and rune information so the wallet can control your Core Lightning Node. In the Remote app in Tor Browser, go to Wallets->Add->Core Lightning. Next click the Advanced link, then select "Direct Connection", then choose "ws".
Next you need to paste in the Address and Rune information. This information can be found in your Core Lightning Properties section on your Start9. Copy the "Remote Websocket URI" then paste it into Remote in the Address field. The Rune from your Start9 can be found in Core Lightning->Actions->Generate Rune. Paste it into the Rune field in Remote, then click "Update". Remote should update to "Connected" if the connection is successful.
If you're on your LAN, start from the Remote app on your Start9 and copy the Interfaces->LAN Address and paste it into a standard browser. Remote should load in your browser. Add a node in similar way as with Tor Browser, except change any .onion address to a .local, and change the "ws" to "wss".