How to install moodle and configure moodledata folder?

I am trying to install moodle on my server. I did unpack moodle package in public html folder. This moodle folder has `755` access rights set. Then I created moodledata folder in the same `public_html` folder and used `777` access right. Then I tried to run install, but I always get `error: Data directory (/home/studentai/***/data) cannot be created by the installer`. But I created it manually. So where is the problem?