Please make sure to update PhotoTV to version 1.9.25 in order to be able to link PhotoTV to Google Photos as the link flow has changed (Roku Home Screen → Settings → System → System Update → Check now).
PhotoTV allows you to display photos from your Google Photos on your Roku TV/device. To set this up, you will need to do the 2 following steps:
1. Connect a new source to Google Photos using a link code.
2. Link albums under your Google Photos source.
At any time, you can modify source and album information, link more sources, albums, etc. Changes to the settings as well as album content will be applied the next time the slideshow/screensaver runs.