To process a PDF score you need a Professional subscription to PlayScore 2.  Please tap the Store button to see options for your country.
You can create playable PlayScore 2 documents from saved photos and images just as you can for photos.
If the scanned images are in your photos, go to the camera screen as if you were taking a picture, but instead of tapping the capture button, tap Photos.  If your scanned images are elsewhere, eg iCloud then tap the import symbol .
Please note: PlayScore 2 needs a high resolution JPG image.  Images smaller than about 1.5M may give poor results.