disclaimer: I have no affiliation with this project !
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never heard of this addon, but it seems to be out there for some months already.
the dropbox link worked for me.
https://pilot-frank.de/produkt/d-mccv-im-flightsimulator-2020-kostenlos/
Since relatively new december 2021, also available on fs.to
https://de.flightsim.to/file/24138/fk9-mark-4
Real Aircraft Info : B&F Fk9 - Wikipedia
This has recently received an update.
It now comes with an extra taildragger version.
And the tablet is working again.
P.S. I noted that when running the automated checklist, one still has to switch on the avionics after doing so.
I flew the new FK9 taildragger version to EDDN (Beta) by Freds Airports.
Thanks for the info. A nice little freeware plane from Deejing. 
Now also at Flightsim.to
I am surprised how much fun this plane is. Really well done. Almost a payware level with only a very few rough edges. I was ready to pass on it but gave it a try and I can see myself flying it often.
Really recommended.