Right.
So it seems your
LFSLazy.exe is not actually in
C:\Users\user\Downloads folder. So the exec command is giving the parameter error when it's trying to execute that exe file while it's not there.
If your
LFSLazy.exe is in the same folder as
LFS.exe - replace
/exec "C:\Users\user\Downloads\LFSLazy.exe" with
/exec ".\LFSLazy.exe"
if it's not in the same folder - you need to specify the whole path so for example if your
LFSLazy.exe path is
C:\LFSLazy\LFSLazy.exe then replace
/exec "C:\Users\user\Downloads\LFSLazy.exe" with
/exec "C:\LFSLazy\LFSLazy.exe"
BTW you don't really need that second
start_LFSLazy.lfs script file. You can use just the autoexec file to start Lazy. So it would look like this:
// This script is run when LFS reaches the main entry screen
// You can use it for initialisations, running scripts, etc.
/insim 29999
/exec ".\LFSLazy.exe"