On occasion, we find the Live Assist for Microsoft Dynamics 365 fails to install if your browser is logged into Microsoft Active Directory more than once, or across multiple organizations.
While you are following the Installation Guide, we recommend you set your browser to Browse in Private before you log into Microsoft App Source and start installing Live Assist.
Sometimes browsers refer to this feature as incognito mode or an InPrivate Window. It allows your browser to run without any cookies or site data that may cause an installation issue.