These login details are to be used to login into your store once you have created it.
So your next step is to create your store with your chosen domain name. In order to do this you need to go to your JVZoo My Purchases Dashboard (https://customer.jvzoo.com). From here click 'View Details' button next to the 'My Product Store' product you purchased. You will then see the purchase details and here you click the 'Access Your Purchase' button. You will then be taken to a page where you can specify the domain name you would like to use for your store. Once you have created your store with your chosen domain you can use the above login details to login into your store via the yourdomain.myproduct.store url.
If you purchased an optional add on's such as Sales Page Builder or Smart Ads, then once your store has been created you can use their respective 'Access Your Purchase' buttons to activate the add on in your newly created store.
Hope this helps clarify things