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 facilitate this cross-platform communication, a companion app must be deployed in the relevant Slack workspaces. This allows Slack users to chat seamlessly with their Microsoft Teams counterparts via the ConnecttoTeams Chat Connector.
This article provides guidance for Slack administrators to install the companion app.
Before You Begin
Prepare your Slack Workspace for automated channel creation. To do this, follow the instruction in Slack Admin Guide for Preparing the Slack Workspace.
You should have received an email inviting you to install the Teamslink Chat app. Alternatively, your Microsoft Teams contact may have shared a direct URL for the same purpose.
Install the Chat App in Slack
Click the link in the invite email or access the given URL directly in your web browser. You will be redirected to a consent page.

From the Workspace dropdown, select the Slack workspace that will integrate with your Microsoft Teams tenant for cross-platform communication.
Click the Install Teamslink button.
Results
Once permission is granted, a Teamslink app appears in the App list of your Slack workspace.

At this point, users in your Slack workspace will be able to connect with users in the Microsoft Teams organization that sent the invitation.