If using a server, ensure the DSLicSrv.txt file is correctly configured in the C:\ProgramData\DassaultSystemes\Licenses folder.
Because R21 is an older release, you should use the : Navigate to the extracted folder and find setup.exe . Right-click setup.exe and select Properties . Go to the Compatibility tab. Install Catia V5 R21 On Windows 11
Again, set it to run in compatibility mode for and check Run as Administrator . If using a server, ensure the DSLicSrv