The Chat App enables Teams Users to exchange chat messages (with rich text and emojis) and share files with users of external chat applications, including Slack.
To enable cross-platform communication, a companion app must be installed in the appropriate Slack workspaces. This app is responsible for creating the necessary channels used for integration.
This article provides guidance for Slack administrators on how to prepare their workspace to support automatic channel creation.
Allow Members to Create Private Channel
In a web browser, navigate to https://<your workspace name>.slack.com/admin/permissions/account-types, enable Create private channels for Member.
To prepare your workspace to support automatic channel creation by TeamsLink, enable members to create private channels in your Slack workspace. To do so, follow these steps:
Open a web browser and go to:
https://<your-workspace-name>.slack.com/admin/permissions/account-typesUnder the Member section, enable the option Create private channels.

Alternative Navigation Path
You can also access this setting through your Slack Admin Dashboard:
Go to your Slack workspace’s Admin page.
Navigate to:
Menu > Manage Permissions > Account Types
Watch this video for a walkthrough of this navigation path.