Purchase event Shopify for Google Ads tag

Hi,

I have created a custom web event for my Google Ads purchase tag, named transactionComplete.

What trigger should I use for the ss tag?

Hi,

It depends entirely on your web setup. More specifically, it depends on the GA4 event that sends this event to the container server.
Judging by the name, it is Purchase, so you must have a GA4 Purchase event on the web container which is sent to the server and the trigger for the conversion should then be event_name: purchase + client name equals GA4