The Process Lasso installer automatically detects and installs the correct edition, so it doesn’t matter which download you choose.
Process Lasso Server Edition will always install on all Windows Server operating systems, and Process Lasso Workstation Edition will install otherwise, e.g. on Windows 10/11.
The only time you need to worry about which installer to get is when you are using the silent/unattended install capabilities. For individual installer downloads see this page.
Note that the installer itself is 32-bit in all cases, but installs 64-bit components as appropriate.