Why is there a discrepancy in my add to cart and checkout numbers?

I’m looking for advices please. I’ve been running this ad for 6 days now. The product is $30. I’ve had a lot add to carts the last few days but only one checkout. However when I checked shopify side it only shows 6 ATC. Can anyone suggest what to do? What’s going on with the discrepancy? I checked un the FB events manager and it looks like the pixel is firing correctly. Help pleaseee. Thank you.