Your website doesn’t get sales because you aren’t taking it seriously enough.
You’ve got the product, the web domain, a Paypal account, and a Shopify website. Where’s those sales at?
Chances are your website doesn’t look pro and has a templatey feel. You are cutting corners and you are missing out because of it.
You can succeed with a great product for sale on a Shopify website but you need help to market it and it will cost you money!