I have an older Mac 10.10.5 operating system I need to update

Back up your data, check the application compatibility table, click here, and then on the download link for a more-recent OS.

Catalina and above won't run 32-bit software; if you choose one of them, use Go64 as well.

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Depending on the age of your Mac, you may not be able to upgrade your software without purchasing a new machine. See https://www.macworld.com/article/673697/what-version-of-macos-can-my-mac-run.html