Hi @IBN
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According to your description, this could be because the chat bot is not added in your Teams first or the organization does not allow to add it in Teams.
In this way, we firstly recommend you contact with your IT admin and check if these apps has been allowed in Teams admin center. You could go to Teams apps > Manage apps to check them. For more details about its steps, you could refer to this article.
Allow or block Microsoft Power Platform apps for your organization
In addition, if you have published the bots in Teams, please check you have connected your bot to the Microsoft Teams channel to allow users to chat with the bot in Microsoft Teams.
Connect your bot to the Microsoft Teams channel
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