The download link of the hpkg file, is on the bottom: please read the whole message
Please notice that, since is an old BeOS app, that will only run on gcc2_hybrid.
Well, I improved this app some years ago: Login system for Haiku
it was an app for BeOS (I’m really sorry, but I don’t remember the name of the original developer 
Then, by myself, I made some improvements:
the first one, as I’ve said, is the modern login mask.
The second improvement, thanks to the package manager system (and to the launch_daemon), is to have Lock Workstation loaded before of Tracker and Deskbar, to ensure that after the Boot, nothing else is displayed on screen, for privacy reason: in this hpkg, I added an “utility” script (named addtoboot present in Deskbar Leaf > Preferences > LockWorkstation > addtoboot ) which will insert Lock Workstation to the /boot/system/data/user_launch/user file and so at startup.
The third improvement thanks to another user/developer (@hey68you), is to have the login screen adapted to your screen resolution.
So, here the download link:
Lock Workstation for Haiku PM - 2017
EDIT: SORRY, THERE WAS AN ERROR WITH THE DOWNLOAD LINK, NOW SHOULD BE OK.
This package is called “lockworkstation2017” to avoid conflicts with any other previous revision: if any other old revision is installed on your system, the package manager will alert you about.
So is recommended to remove any “lockworkstation” package from “/boot/system/packages” folder.
After that, when you will install this hpkg, please read carefully the readme on Desktop: I also implemented a way to skip the login screen in case of emergency.