I have a 2014 or earlier Mac Book. Can I do the update 15.6.1?

15.6.1 is for iPads and iOS devices, not Macs.

If you're referring to Monterey, no.

If you're trying to get the recent security patch, Apple will release a version for older systems if they consider it necessary.

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There are no 2014 MacBooks. MacBooks are from 2006-2010 and 2015-2017.

Perhaps you have a MacBook Air or a MacBook Pro.