well, first I suppose you need to enable 'Tool Options" tooblar, as most of options for these commands are located there.
Using the tool options toolbar, you may specify desired align options.
The logic of actions is quite straightforward - first select entities to align, ENTER to complete selection, and select entity to aligh (or what is expected by the tool options).
You may follow prompts that describes expected user action that are shown in command line, or in Mouse widget, or in Informational Cursor (of course, given that they are enabled).
If you see some issues with these (other other) functions - please report them directly to GitHub -
https://github.com/LibreCAD/LibreCAD/issuesYet it's strange that I didn't prepared a demo for this command...