Answers
HighLevel: making a WooCommerce sale start your automation
When WooCommerce Sync sends a sale to HighLevel it does two things: it creates an invoice for the customer, then records the payment against it. The invoice lands as a draft and the payment is what makes it real. Nothing about that is automation on its own, it is bookkeeping. This is how you make it start a campaign.
Build the workflow off the money, not off the invoice
In your location, Automation → Workflows → Create Workflow, and add the Payment received trigger. Not the Invoice trigger. The Invoice trigger fires on creation, sending and overdue reminders as well, and it can only filter on invoice status and contact fields, so it cannot tell you what somebody bought. Payment received activates when a payment record posts successfully, which is the moment money actually arrived.
Always set a filter, or it fires on every payment
A Payment received trigger with no filter at all fires on every payment in your account. Every sale, every product, every customer, into the same campaign. Buy a t shirt, get the course welcome sequence. So a filter is not optional.
Filter on the tag we apply, not on Global product
The trigger offers a Global product filter and it looks like the obvious answer. For sales synced from your store it does not work, and we tested it rather than assuming: with a workflow filtered to one product, a paid invoice carrying that product fired it and a paid invoice carrying something else entirely fired it too. HighLevel's own enrollment history showed both contacts entering the same workflow. That filter reads the products on HighLevel's own checkout orders, and an invoice we record a payment against does not populate them.
So filter on the tag instead. WooCommerce Sync applies a tag of your choosing for each product it syncs, that tag lands on the contact with the sale, and a workflow that triggers on Payment received and checks for that tag fires for that product and nothing else. Set the tag on the product in WordPress, use the same tag as your workflow filter, done.
Then do whatever you like
Apply a tag, start a campaign, send an email, notify somebody, move an opportunity. HighLevel does not care that the payment came from your store rather than from a funnel, which is the whole point: your marketing runs off the money, and it keeps running that way whether we are in the picture or not.
If you are coming from Keap
Keap does this with a Product Purchase goal set to paid invoices only, and the shape is the same on both: the sale syncs, the payment records, the automation fires. The wiring differs and the idea does not.