Hi,
I managed to get it running on my DS214+. The problem was the missing "
FastCgiExternalServer" in the apache configuration because of a wrong path in /var/packages/IDrive/target/app/.scripts/pathchanges.pl.
In this file I replaced line 180:
my $update_file = "/etc/httpd/conf/extra/mod_fastcgi.conf";^M
by
my $update_file = "/usr/local/etc/httpd/conf/extra/mod_fastcgi.conf";^M
and voila, it worked.