Dear ejn63 and jphughan,
Thank you guys for the quick and useful responses!
Both of the solutions works, however I chose the simplest one, ejn63's,
and created a bootable pendrive with the use of Microsoft's media creation tool. The machine now recognises the USB drive and installing Win10 was quick and easy.
The only - minor - disadvantage with the MS tool is that it doesn't allow you to chose your own image from your machine, since it downloads an image (a multi-version one) from MS. I wanted to install my own copy of windows 10 Enterprise.
Anyway, I'm very satisfied with the version I finally installed.
Thank you again very much.