Notaku supports protecting your docs site with a password.
To add a password go to your site settings tab and put the password you want.
You can then distribute the password to your users and give them access to the site.
Notaku still requires your Notion pages to be public, this is not a problem as long as you keep the Notion url secret
If you change the password of your site while some users are already logged in they will lose access, you will need to distribute them the password again
Is password protection available in the free account?
No, password protection is available only on Notaku paid plans.