Chat between agents and users is available through the Messenger widget on your Help Center or sites you have embedded it on.
However, the tab isn't always there. It's only shown when the user has the correct permissions to use chat.
If you aren't seeing Messenger on the Help Center when you would expect to, check the following:
1. Make sure chat is enabled. In admin, check the control in Channels > Chat > Messenger Setup & ensure Messenger is enabled and you have it selected to show on your website and/or Help Center.
2. Check the Usergroup permissions for the user who cannot see the Messenger Widget (in admin, check CRM > Usergroups > Permissions > Chat).
For a logged-in user to see the chat widget, they must be a member of a Usergroup with the chat permission enabled.
3. If you want guests (i.e. anyone who's not logged in) to be able to see Chat, ensure the Everyone group is enabled in CRM > Registration and that it has chat permission.
4. Are the correct chat department permissions enabled for at least one department in Channels > Chat > Departments > ‘Select a department’ > Permissions
Once you have made these changes, your users should be able to see the Messenger Widget on the Help Center.