to make bootable USB stick use Etcher, what you need?
1. Tails OS for Mac >> https://tails.boum.org/install/mac/usb-download/index.en.html
2. Etcher >> https://github.com/balena-io/etcher or https://tails.boum.org/etcher/Etcher.dmg

Don't forget to verify all downloads.

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For Linux user can use Startup Disk Creator already has ubuntu store or use command line dd
https://tails.boum.org/install/expert/usb/index.en.html

when tail os already on a USB stick, easy way to make it by clone