You can add people to a space, you can select people from your organization, or enter the email addresses of people from outside your organization that you want to invite. Each space can have a maximum of 5,000 people in it.
Go to Messaging , select a space, and then click People.
Click Add people , type the first letters of their name or their email address, and pick them from the list. If you selected someone that you don't want to add to the space, click their profile picture to remove them.
To invite people to Webex, type their email address and press Enter. After they join Webex they'll see your space in the app.
Click Add to add your selected people to the space.