I hope you mean LESM/save/Users.json cause Users.db is not with my lua, and in silent if you edit that it gets corrupted not sure how it works in nitmod though.
Any changes manually made to Users.json (while the server is online) will not take affect, since it loads Users.json at the start and saves it at the end (Overwriting anything you would have made). It really wasn't meant to be Edited like the other files.
To set up the first authorized user it needs to be done through rcon:
lua update bluemax authorize true
Then from then on you can update other people via
/lua update username authorize true
(By the way authorize is meant only for server operators, as it has a lot of control)
After that you can do !config help to see a list of config options. and !config balance for example to see a list of options under the balance category.
And then !config balance.enabled true to enable balance.
(important) And then !config save to save the config.
Will add this all to the wiki in a more complete manner later on, I am just procrastinating big time sorry