To pin the CloudRadial Portal app, you'll need to tweak the app policies in your Teams Admin Center for your client.
You can access the Teams admin center through https://admin.microsoft.com.
- Go to Teams Apps.
- Setup Policies.
- Set the default pinned apps:
- select Add apps.
- In the Add pinned apps pane, search for the app you want to add, and then select Add.
For more details click here: Manage app setup policies in Microsoft Teams - Microsoft Teams | Microsoft Docs