In Windows 10 I had eMClient start as the computer started, but in Windows 11 it doesn’t. The app does not appear in the Startup list.
Go to “Menu / Settings (Preferences) / General” and check the box “Run on system startup” and Save Settings as per the example V10 below.
If that doesn’t then automatically startup when Windows 11 loads, then you might have a eg: registry problem.
You can alternatively put the “eM Client shortcut” in the Windows 11 startup folder manually via following the Microsoft support page on various ways to manually launch apps on startup.