Thanks for reaching out here and welcome to the Shopify Community.
I can see that you are hoping to use the ‘epay E-commerce Euronet’ payment gateway on your store in Greece - I would be happy to help clarify this for you.
On Shopify, the availability of payment gateways can vary depending on your store’s region. While Shopify supports a wide range of payment gateways, not all gateways are available in every country or region. When setting up your Shopify store, you would need to choose from a list of supported payment gateways based on your store’s location, in this case Greece. Please find the full list of available payment gateways in Greece here.
I had a look through the list and do not see mention of a ‘epay E-commerce Euronet’ gateway. However, there are some popular gateways available in your region such as Stripe, Authorize.net, 2Checkout and PayPal Express Checkout. The availability of specific payment gateways may change over time as Shopify expands its partnerships and adds support for new regions, but for now you will need to choose one from the list linked above.
If you need some guidance with setting up the gateway after you have selected it, we have some great info here on our help center about third-party gateways. Of course, reaching out to the payment gateway directly with any specific questions would be a good idea, as they will be the best equipped to assist. If you are new to Shopify in general, I would highly recommend this YouTube tutorial as it’s a great place to learn the steps involved in getting a store ready to make sales!