Open custom button in new tab

Hi there.
I am designing an ecommerce website with some third party generated buy buttons. I am using the html embed to insert the code that payu gives me to insert the button.
Once I click on the button it goes straight to the checkout process and takes me out from the website. Is there any line of code I can insert to prevent this and have the checkout to open in a new tab?

This is the whole code I am pasting on the embed element:

Thanks a lot for any help!