If you already have Windows 10 installed and just need to update to version 6.1, you don't need a USB drive. Open Apple Software Update
The easiest way to get the correct version of Boot Camp (like 6.1) for your specific Mac hardware is through macOS: Open Boot Camp Assistant : Located in Applications Download Support Software : In the top menu bar, click Download Windows Support Software Save to USB Bootcamp 6.1 Download Windows 10
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: First, ensure your Mac is compatible with Boot Camp and can run the version of Windows you're planning to install. Apple provides a list of compatible Macs. If you already have Windows 10 installed and