If you're an admin for your organization's Webex Teams, go to https://admin.webex.com/settings.
Scroll down to the section that says External Communication.
Under Block external messaging, make sure the switch is turned off.
Under Whitelist domains for external messaging, make sure you add m.io domain name.
If you're having issues working with the Mio Universal Channels app after following these steps, please email firstname.lastname@example.org for more assistance.