Hi @blitzmr2,
Thanks for reaching out.
Unfortunately, the Sellings Ads add-on connects only with WooCommerce. Since Upsell has only a paid version, I doubt that we will integrate with it in the future.
If you can do without the semi-automation of Selling Ads, which transforms an order into an ad when an ad product is purchased, I would consider building that manually.
If you can create products in Upsell and the plugin provides a shop function including payment options, it only requires direct communication with the customer to get the ad code.
Best regards,
Joachim