with the game comes the bonus.zip file. This is the pre sale bonus with an extra quest.
However when I go to run the exe file it ask for a path to install, no matter where I pick, it comes back with an error

Unable to Execute file
CreateProcess Failed code 87
the Parameter is incorrect

I have windows 10
I ran as admin and comp mode to see but same error

any advise?

Same issue here. Win 7 64-bit.
Running BonusSetup.exe in compatibility mode did not help.
Process creates an empty new folder and that's all.

Someone else found it had put the file in the wrong place: https://www.gog.com/forum/lionheart_legacy_of_the_crusader/having_issues_with_the_bonussetup_file/post2