Follow these steps to animate 2D instead of 3D models upon scanning a marker:

1. Drag and drop your 2D animation into the Resources panel from your computer to add it to the project.
2. Delete the 3D assets from the template in the Objects panel by right clicking on them, and pressing Delete.
3. Select MarkerWithSnapcodeController in the Objects panel.
4. Press Add new > Image in the top left of the Objects panel.
5. Select your new image in the Objects panel.
6. Click on the Texture field in the Inspector panel.
7. Select your newly added image in the popup window.
8. Resize and move your 2d animation in relation to the marker in the Scene panel.