It seems the link to the RS232 to TTL converter went stale. I am ordering this one instead: https://www.aliexpress.com/item/RS232-To-TTL-Converter-Module-COM-Serial-Board-MAX3232-MAX232CSE-Transfer-Chip-atmega16/1920204765.html?ws_ab_test=searchweb0_0,searchweb201602_2_10037_10077,searchweb201603_1&btsid=af8a76b1-c9b5-4ea7-9c5b-209cdc11d1f1