When signing in to connect your Google Account, the security is managed by Google and your password is not shared with Capture.  

Only those with access to the Google Photos account you connected with your digitized memories will be able to view your memories in the account. In addition, those you chose to share your memories with during the activation process, will also have access to your digitized memories. 

 Rest assured, if there is any instance where you would like to remove anyone with access, you are able to do so.