I've followed the instructions here : https://support.apple.com/en-au/HT204990
I have a late 2013 MacBook Pro Retina. Currently running Windows 7 64bit. I've got the latest OS X 10.11 El Capitan, all software updates applied. I've run the Apple Software Update in Windows 7 - all up to date.
When I click on the Get Windows 10 icon, it displays:
"Unfortunately, this PC is unable to run Windows 10... because one or more things are incompatible.
Viewing the report, it says:
"The device manufacturers haven't made these devices compatible with Windows 10, so they won't work. Check with the manufacturers for support."
Apple Broadcom Built-in Bluetooth