That's a file permissions problem. I suspect you can't install anything presently. This is a server configuration issue.
Either the file/folders aren't owned by the webserver user (likely) - or the website tmp directory has the immutable bit set (unlikely).
run this command:
ps aux | grep apache
ps aux | grep httpd
You'll see several lines that begin with something like www-data, apache, httpd - this is the user who owns the web server process. To allow the web server to write to the Joomla install folders, those folders need to be writable by the web server user.
So, lets say you're running Ubuntu - the web server user will be www-data. The www-data user is a member of the group www-data, so if you change ownership of the files to the www-data group - and change permissions to g+w, you'll be golden.
The command to change ownership of the files to www-data group is: