SecureLogin has three options for providing single sign on to web pages in Internet Explorer for which end user have to set a DWORD IESSOBHO in registry(HKLM\SOFTWARE\Protocom\SecureLogin)

1. Set IESSOBHO to 1 and interface with IE through the SecureLogin IE add-on, This is the default settings.

2. Set IESSOBHO to 0 and integrate directly with IE through the SecureLogin Windows process (slwinsso.exe). This option is typically chosen in environments that do not allow the addition of IE add-ons.

3. Set IESSOBHO to 2 to integrate with embedded browsers while the SecureLogin IE add on is enabled. SecureLogin works through the BHO interface for iexplore.exe but through the windows process if application name is different (Embedded browsers).

Specific use case:

Suppose the end user have an windows11 box where he needs to do SSO in Microsoft Edge with IE compatibility mode on.
In this scenario there is no IE. When IE compatibility mode is enabled in Edge, an instance of IE 11 runs and renders the site in a tab. This is similar to second option of setting IESSOBHO to 0.

So if user sets the IESSOBHO to 0, SSO will happen seamlessly.