The option FollowSymLinks is enabled by default on DirectAdmin servers. The main requirement for this to work an owner of a symlink and a target file/directory should match. In other words, you can not use symlinks to cross-link content between different users.
AH00670: Options FollowSymLinks and SymLinksIfOwnerMatch are both off, so the RewriteRule directive is also forbidden due to its similar ability to circumvent directory restrictions