From the customer view in https://admin.webex.com, go to Organization settings.
Scroll to Network location and enter your IP addresses or ranges.
Go to Services and on the Message card click Settings.
Scroll to Collaboration Restrictions and turn on the toggle Restrict file sharing to your network only.
IP range or address-based restrictions only apply to file upload, preview, download and to whiteboards and annotations.
IP range or address-based restriction does not apply to sharing animated GIFs and previews for shared links.
Prevent People From Sharing Files Outside Your Corporate Network
With Pro Pack for Cisco Webex Control Hub, you can include the IP ranges for your organizations network and ensure that people can't share files in Webex Teams, when people are not on the corporate network.