Try to run setup.exe and get error message say Domino 5.08 or later need to be installed.
Actually, R6 has been running well.
Subject: R6 and Symantec AntiVirus/Filtering 3.0
The version 3.0 doesn’t support R6. You need Symantec Antivirus/Filtering for Domino 3.1.0 to use on R6.