Hello Achim,
First of all, welcome here.
- I recommend you read my post
BTLE Adapter ATR833 - VFRnav ...so funktioniert's, even if you don’t have the adapter. You must under no circumstances try to establish a classic Bluetooth (BT) connection via the OS!
- I don’t know of any good experiences with the BT “box” — we couldn’t get it to run for a friend either! (not with VFRnav and not with any other program)
- Get Hermann’s adapter from the shop and be perfectly happy. https://shop.flugbetrieb.com/de/
Happy flying
Karsten