By default, the sender’s wallet will try to communicate with the receiver’s wallet via Tor. If the connection succeeds, all the rest is done automatically by the two wallets and no manual action is required. The process is exactly as described above, but it all happens under the hood without further intervention.
However, if the Tor connection between the wallets is not successful for whatever reason, grin defaults to manually exchanging slate text messages, also called slatepacks. This manual process is the same without a grin1 address.
(1/3) Sender shares with the Receiver the slatepack displayed at the end.
(2/3) The Receiver introduces the slatepack shared by the Sender. Then, the Receiver share the returned slatepack with the Sender to finalize the transaction.
(3/3) Sender finalizes the transaction.