Hi Rovolita! Thanks for posting in the Canon Community Forum. The TS9520 is not capable of Auto Duplex Scanning. The IJ Scan Utility Lite manual that you are referencing is a generic manual for the application. Not all features of that manual are available for your printer.
In step 5 of the article that you mention, it says you can alternatively select ADF Manual Duplex from the Select Source. If that options is available, you may be able to scan one side of the pages, and then manually turn the document over to scan the reverse side.
I hope this information helps. Thanks for choosing Canon.
