Mac Desktop Plugin "Zoho.app" is damaged

I've just signed up to test Zoho Assist as a solution in our Apple Mac environment and cannot install the Mac Desktop Plugin from Zoho.dmg. The error message is below:

“Zoho.app” is damaged and can’t be opened. You should eject the disk image.

“Zoho.app” is on the disk image “Zoho.dmg”. Safari downloaded this disk image today at 8:21 AM from meeting.zoho.com.