Merge pull request #64480 from dfitzmau/OCPBUGS-18560

OCPBUGS#18560: Added important vSphere note about AD username integra…

Author: michaelryanpeter

modules/installation-launching-installer.adoc

@@ -429,6 +429,14 @@ ifdef::vsphere[]
 .. Specify the user name and password for the vCenter account that has the required permissions to create the cluster.
 +
 The installation program connects to your vCenter instance.
++
+[IMPORTANT]
+====
+Some VMware vCenter Single Sign-On (SSO) environments with Active Directory (AD) integration might primarily require you to use the traditional login method, which requires the `<domain>\` construct.
+
+To ensure that vCenter account permission checks complete properly, consider using the User Principal Name (UPN) login method, such as `<username>@<fully_qualified_domainname>`.
+====
+
 .. Select the data center in your vCenter instance to connect to.
 .. Select the default vCenter datastore to use.
 +