We did this on our laptop, but used our phone to take a picture of the CDC card. You could download a picture of your card into your laptop from a camera. We had to send ourselves an email of the picture and downloaded it into the laptop. You enter your personal info, passport info, vaccination history(dates, type) into the start of the app. Downloading the CDC card was the hardest part, but they provide a link. You have to claim if you are entering by land, sea or air. You also need the name and address of where you will isolate if needed. At the end, you should get a QR code that you can print and show at the border. I think you should have your original CDC card and passport as well. It is a challenge! You can enter the basic info, but the last steps have to be within 72 hours of your arrival into Canada. You can try a dummy trip and just logout at the end. I found out at the end you can enter all of your party on one application, we ended up with separate accounts.