In the Cart and Checkout blocks the offer sits in the order summary. The totals update right away when the box is ticked, and the fee shows as its own line.
In free mode there is no box and no fee, just the badge. The guarantee applies to every eligible order.
On the classic cart and checkout you pick the position. The box follows the shipping country and the totals as they change.
The offer is hidden for carts with only virtual or downloadable items, for local pickup, for countries not on your list and outside your cart value limits. After the order the choice is forgotten, so the next order starts unticked again.