To add cards to your page:
click on the cards block button (1)
write a title for your cards block (2, 2.1) (you can have multiple cards in one card block)
add cards by clicking add card button (3)
For each card you can add:
Important! When you add a link (10), it should be a full link to the website, starting with http or https (11) as you copy it from the browser's address tab (12)
You can add a link OR a file in each card.