The only file that the ml_local_291.exe installer contains/installs is ml_local.dll to the %ProgramFiles%\Winamp\Plugins folder.
You can use 7-Zip
to manually extract ml_local.dll, if you wish...
Sorry, but the above attachment is the only version of ml_local.dll v2.91 available
and the bug is definitely fixed in that.
(latest internal version is v2.92 and includes features/code which will only work with the next release of Winamp)
You probably need to run the installer as admin (via right-click menu) so it'll have permissions to write to %ProgramFiles%\Winamp