We could not process the request for the selected shipments. Please add a card on file first

This errors means that  you'll have to add a credit card on your Shippsy account.
In order to proceed, you'll have to login to your Shippsy account, click on PAYMENTS on the left side panel and click ADD CARD.
After adding a credit card on your account, you can go back to the "Action Required" tab and click on "Request" to confirm that you want that specific shipment to be imported to Canada.

If you have existing credits on your account, you will still be required to add a credit card.