How to allow customers to add multiple physical products to Card before checkout

Hi,

I am having hard time finding a way to set up my store in a way that customers could add multiple items to their card before checking out.

I appreciate your help in advance 

It sounds from your description that you may have Express Checkout enabled?

https://support.squarespace.com/hc/en-us/articles/206540817-Express-checkout

That would cause a user to go directly to checkout after clicking purchase, rather than allowing them to keep adding to their cart.