A newbie – can’t find zip install option

Just discovered this app and site – installed on a Mac.

I see instructions on how to install an Add-On that includes installing from a zip file as part of flow. Example:

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Go back to your Home Screen and then to SYSTEM > Add-Ons > Install from Zip File > “MD” > Repo > mdrepo-1-0-x.zip and wait for the Add-on enabled notification
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Problem is that I don’t see an install from zip file option in the Add-Ons menu, or anywhere else for that matter. Where do I find this option?

Thanks,

Newb