@jazzi
Can I ask you to post the contents of temp/composer.log?
Alas, fopen(), used by Pockethold seems to be working, as composer has been downloaded.
proc_open() is used by composer (This was new to me), and I am not sure if there is much I can do if proc_open() is indeed blocked by your host.
Again, I am not sure if I can help until I see the error log.