This is the first time i am working with wordpress and i am a bit confused about this requirement.A weird requirement by the plugin indeed Its asking me to :
Files and directories could not be automatically created to complete the installation. Please enter FTP details below to complete the setup. Also try chmod 777 /var/www/my-project/wp-content
Well i am not sure that its safe to give permission 777 to my wp-content folder. It is really required?
I idea is that you set 777 permission on the wp-content dir while you do the install and then revert the permissions.
Dont worry !!!! It is not asking permanently.You have to give this permission for the installation time only as it have to write things in your wp-content.After installation it will tell you to make it back to the default 755.Probably the massege will appear like this in your case.
So start installing. and be happy :-)