To  password protect a directory htaccess password protect rules can be added in the directory

AuthUserFile /path/to/.htpasswd
AuthName "This is Hasten secret area"
AuthType Basic
require valid-user

To create .htpasswd file  use the following command

htpasswd -c .htpasswd  <user>

You will be prompted for password . Once it is done, the file will be created.

Now the directory is password protected.

Allow Subdirectory

The restrictions imposed on a parent directory will be applicable to the subdirectory too. To override this we need to specify it in .htaccess in the subdirectory. To disable password proptection on subdirectory , add the following in .htaccess

Allow from all
Satisfy Any