How do I set my own link for a button or add a second button in a product pop-up in the ST3** block?

There is no possibility to change the action for the button of a product card pop-up in ST3** blocks, unfortunately. When opening the product card pop-up, the "Add to Cart" button will be displayed by default. The functionality of ST3** blocks cannot be used to assign a link for the button or add a second button. When clicking on the button in the pop-up, the product will be added to the shopping cart. 

If you need the option to assign your own link in the product card pop-up, you can use the  ST2**, ST4**, or ST5** blocks — separate product card pop-ups.

Note that the recommendations described above are applicable only if you create products directly in blocks, without using the catalog. If you connect the product catalog to the ST3** blocks, a pop-up with the "Add to Cart" button will open by default and you cannot change the action.