I had a lot of problems when I was trying to BUY CBD stuff. I've discovered that it's barely impossible because of PayPal and Stripe rules. BTW, I understand, why they have those rules. It's because CBD oil highly likely will contain some percent of THC, which actually is a drug, because it makes you high. CBD is good for relaxation and relieving the pain, but you must prove that it doesn't contain THC. I've ended up buying CBD gummies Europe produced direct from the manufacturer, BTW. Because I didn't found out how to buy it using PayPal.
Best way of selling CBD Oil based products on ShopiIfy stores is having your own preferred payment gateway integrated to your store.
See below two steps.
1) Find a any suitable merchant/payment gateway provider who can offer you a merchant facility for your CBD OIL or any kind of high risk products
2) Integrate above preferred Merchant/Payment gateway to your Shopify store ( Send me a message, I am happy to assist with you in regards to integrating third-party IPGs to Shopify stores)