To access your digital copy in the Marvel Comics app, please sign in on the app with your username and password and go to "My Comics." Look for the comic by title. Once selected, download the digital comic.
The Marvel Comics app on the iOS and Android stores are available for download here:
iOS: https://apps.apple.com/us/app/marvel-comics/id350027738
Android: https://play.google.com/store/apps/details?id=com.marvel.comics&hl=en_US