I posted the below comment to the topic suggested by @Reinhard-32 , but that forum does not seem to be very active, so I thought I copy it to here as well:
@Sergio-Resende Hi, I tried this with my Navigator V, and I get the following message: 'File Sharing Not Supported. Your navigator doesn't support file sharing functionality. Connect a compatible navigator to share the file'.
It seems, that BMW Navigator is not capable for such file transfer, it only works with other Garmin deices.
@Reinhard-32 What is exactly OTG adapter? Is it the one called Lightening to USB 3 camera adapter? I tried to connect m)y Navigator to the iPad by an other adapter, called Lightening to USB adapter, without success.
It said that 'This accessory requires too much power' Did you use the USB 3 adapter, having a USB-C inlet, where you can also power it from an external power source?