Didn't knew about this. They say that the API-Key is not stored. I would check if the Backup runs in your browser (which would be ok) or if it runs on their servers. With the last implementation I would never use it from a more or less anonymous system.
Also look at the script that @PhilipDAth provides:
https://www.ifm.net.nz/cookbooks/meraki-backup.html
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