Zoho GDrive apps on Google Drive, is incorrectly set to support only Chrome (leaving out FF & IE).
The issue is very likely caused by the Zoho apps deployed (as found via the Chrome Web Store) was deployed using "CHROME" instead of "DRIVE" in their manifest.
In short: Zoho is currently off-limits to all users except those using the Chrome browser.
And we all know that Zoho's applications as found here under *.zoho.com work with all main browsers.
If this is not corrected, then Zoho is effectively limiting their audience to less than 1/3 of their potential (and that's just stupid).
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BTW: Other developers have made same mistake, and some has already corrected the mistake.
One example is a comment like (link)