yes you see it right!
ok lets get it fixed!
1. memory limit you said you changed in php.ini or in php config somewhere on public folder,
CHECK AGAIN - if you are using virtualmin/webmin/cpanel and as "virtual host" different setting override the default values in php.ini so check on virtual site's php option
2. the tmp file, where's your virtual site's temp folder? check it if not using the system wide /tmp and is inside the virtual host change to 777 and just change back after installing.
3. check components folder. change to 777 then after install change to 755
