On Shopify, the option to checkout with Sezzle is at the very end of the order process - after the shopper chooses their shipping method, on the same page where they could enter their credit card information.
If we don't show up at that point, it's likely that the Sezzle gateway hasn't been fully installed. To get that configured, please log in to your Sezzle account and go to your “Setup Checklist” (or click here) and go to step 2 – that will then walk you step-by-step through adding us to your Shopify checkout.
Additionally, if the shopper has opted into Shopify Pay, or if they have a Shopify account and preset checkout settings, they might not see Sezzle (or any other payment methods, like GooglePay) at checkout. In those instances, we recommend that the shopper checks out as a guest or uses a private browsing session to be able to checkout with Sezzle. If you have further questions on this setting, we recommend reaching out to Shopify directly.