Hi @it magic!
Here’s our Help Center article on this topic if you’re interested:
From the article:
Most pre-built abandoned cart flows trigger based on the Started Checkout metric, which triggers when someone enters their information at checkout and moves to the next step of the process, but some ecommerce integrations track the Added to Cart metric, which triggers when someone adds an item to their cart but doesn't place an order. If you are using Shopify or BigCommerce for example, you will need to set up this metric manually.
Since you’re using a custom integration, you may be lacking a metric that can trigger the flow, like Started Checkout or Abandoned Cart. I would start by confirming that one of those metrics is in your account. If it’s not, you may have to create it from scratch using these developer guides:
Best,
Brian