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 
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Please note: PlayScore 2 needs a high resolution JPG image. Images smaller than about 1.5M may give poor results.