Unlike specific hardware components like a graphics card or a printer, which require unique manufacturer-specific drivers to function, USB mass storage devices (flash drives, external HDDs, card readers) utilize a standard protocol defined by the USB Implementers Forum (USB-IF).
Microsoft does not offer a standalone "download" page for this driver on their official website. Why? Because it is part of the core operating system. Third-party websites claiming to offer a "USB Mass Storage Device Driver download" are often bundling adware, malware, or simply repackaging what Windows already has. usb mass storage device driver windows 10 64-bit download