Hi @Guavity
Welcome to our forum!As i know: You can use Outlook for Windows to schedule an online meeting using either Skype for Business or Microsoft Teams, depending on what's supported in your organization. This can be changed by the organization's IT administrator to set Teams as the preferred service.
More information: Create or schedule an online meeting in Outlook for Windows - Microsoft Support
In addition, if your client's organization uses Teams, but your client is not properly visible in Outlook, it is recommended that please follow this article to try to fix it: Resolve issues with Teams Meeting add-in for Outlook - Microsoft Teams | Microsoft Learn.
Hope it helps!
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our [documentation] to enable e-mail notifications if you want to receive the related email notification for this thread.