On the Home screen, tap one of the 5 big cards: Scan with Camera, Sign a PDF, Password Protect, PDF Converter or Extract Text (OCR).
Tap Choose files and select all the files you need (you can select several at once).
Choose Text.
Tap the big purple Start button and wait a few seconds.
When you see Done!, tap Download. The new file is saved on your phone or computer.
Note: a scanned PDF is only a picture, so it has no real text. Run Extract Text (OCR) first if Word/Excel comes out empty. Complex layouts may change a little.