The latest version is here https://www.zen-cart.com/showthread....47#post1366247
and was last touched by drbyte, but its not really his he was just updating it. I have it working ok on my 1.5.7/php 7.4 production site, but can't get it to work on my 1.5.8/php 8.2 dev site. We may have to pay more to use shipstation just cuz it works.
Also note, we are off thread topic here. Sorry all.