File transfer (not photos) issues from iPhone Pro Max 12 to Windows 10

Apple iPhone 12 Pro Max 12 will not transfer files from iPhone to Windows 10 using Wi-Fi or when tethered iTunes.

Wi-Fi method:

1. Both the iPhone and Windows 10 recognise each others BT (connect)
2. I specify Windows 10 BT to receive files
3. I then go to the Files App in the iPhone,
4. I select the PDF to transfer from iPhone to Windows 10
5. I then select 'AirDrop' (note that in the 'More' 3 horizontal dots, there is only AirDrop, Messages, DuckDuckGo and Outlook applications)
6. I select the AirDrop App
7. What's returned is 'No People Found'.

Tethering method:

1. iPhone is tethered to computer (Windows 10 OS) using iPhone's Lightning cable
2. iTunes is loaded
3. iPhone selected in iTunes
4. iPhone icon selected (bringing up iPhone summary) and 'Checked for Updates (none)
5. Backups set to 'Automatically Back Up' with 'This Computer' specified
6. 'File Sharing' in listbox (right hand side) selected.
7. In 'File Sharing' the 'Apps' and 'Documents' are both empty.

What do I need to do to be able to transfer files (not photos) from my iPhone to computer?

Thanks in advance.