Looks to me you're using an Enterprise edition of Win 10, which doesn't allow - by default - connection using the guest account to file shares.
You may try using WinSCP to connect to your Pi and copy your ROM/BIOS files over.
Contributions to the project are always appreciated, so if you would like to support us with a donation you can do so here.
Hosting provided by Mythic-Beasts. See the Hosting Information page for more information.