Yes you can protect a folder with password through Helm CP using the following steps.
1) Loging on Helm CP
2) Click On Domain Option.
3) Select a particular Domian in which you want to Protect a folder.
4) Click on Secure Folder option.
5) Enabled the Status of Secure Folder and then click on Save Button.
6) You will get three options.
(a) Select a particular folder from Folder option on which you want to apply security.
(b) You can create the users from Create Users option who can use the particular folder.
(c) You can create a group of users using Create Group Group option, in a group you can include multiple users and you can allow multiple users to use the folder.
Now when any user wants to use that particular folder he has to use user name and password.