The Truepic Vision app is free to download, so you should not have to pay to do so. If you are unable to download the app because you are told there is a payment method needed, it could be because you have not downloaded an app with your Google account previously.
Android devices should have the option to "Skip" adding a payment method when downloading the Truepic Vision app.
If there is any cost shown for downloading the Truepic Vision app, please contact Truepic Support before going through with this, as it could be a sign your device is compromised.