Hi, @jackiesaik .
Thank you for sharing your experience here. I understand that the ideal is to create Canada Post manifests through the Shipping Manifests app rather than installing a third-party solution. While I don’t have an update for you right now, I will share your thoughts with our developers for consideration in future changes.
Have you looked at any of the free to install apps like Shippo? Apps that note additional charges may apply are likely referring to label purchases. I don’t know whether charges also apply for creating manifests, but it’s worth a look for now.