Why gigabyte & why 2400G? 2400G is only recommended if you are not going to get a dedicated graphics card later.There are better options than b450m ds3h for similar/bit more price.
Just disable secure boot in mobo uefi settings & once win 10 is successfully installed,turn it back on.Rufus with latest win 10 versions now needs this turning off of secure boot because latest win 10 ISOs now contain a single file larger than 4gb making rufus need to format usb as ntfs which is incompatible with secure boot(there are other tools which can bypass this restriction by splitting the win 10 iso into smaller than 4gb file parts but I think rufus is better for a typical user,just don't forget about secure boot).