The credit card collect payment allows you to retrieve the credit card information in order to process the payment manually via your own terminal.
If you want a credit card processing payment method, you need to open an account with one of the payment gateways supported by HikaShop like PayPal, authorize.net or cardsave and you will be able to propose credit card payments on your website with HikaShop with the payment processed automatically.
HikaShop doesn't verify the credit card, it's the payment gateway which does that, like for all the other ecommerce solutions, even on wordpress.
Maybe you jpg image is too big for your server upload restriction ? In any case, if it works for pngs it should also work for jpgs.