php and w3 cache path location issue?

HI, I am running a wordpress multisite on a VPS with debian 6 and ISPConfig 3.

I wish to install w3 total cache, but i am having issues with php mode.

If i run site in mod-php i get permission errors:

w3 plugin page

ERROR: The Snapshot destination folder is not writable /var/www/clients/client2/web2/web/wp-content/uploads/snapshotsERROR: The Snapshot destination folder is not writable /var/www/clients/client2/web2/web/wp-content/uploads/snapshots/_backupERROR: The Snapshot restore folder is not writable /var/www/clients/client2/web2/web/wp-content/uploads/snapshots/_restoreERROR: The Snapshot destination folder is not writable /var/www/clients/client2/web2/web/wp-content/uploads/snapshots/_logsERROR: The Snapshot destination folder is not writable /var/www/clients/client2/web2/web/wp-content/uploads/snapshots/_logs/_sessionsERROR: The Snapshot locks folder is not writable /var/www/clients/client2/web2/web/wp-content/uploads/snapshots/_locks
FTP credentials don't allow to delete folder /var/www/clients/client2/web2/web/wp-content/cache/config
W3 Total Cache Error: Files and directories could not be automatically created to complete the installation.

w3 compatibilty check

WordPress Resources

/var/www/clients/client2/web2/web/.htaccess: Not write-able
/var/www/clients/client2/web2/web/wp-content: Not write-able
/var/www/clients/client2/web2/web/wp-content/uploads/2015/05: Not write-able

If run it in fast-cgi mode it cannot find apache modules

w3 compatibility test

mod_deflate: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_env: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_expires: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_headers: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_mime: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_rewrite: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_setenvif: Not detected (required for disk enhanced Page Cache and Browser Cache)

I do have ftp details in wp-config.

Is it possible to run w3 total cache in fast-cgi, if not how best to permissions working with mod-php?

thanks