My server only allows clans of max 4 but not friends to prevent ally's/zergs , can I use this with clan support?

Added in 1.1.0, thanks for your suggestion!

Only the clan plugin linked on the page under works with. Im pretty sure Rust:IO has it's own friendly fire plugin that works with the Rust:IO clans plugin

Edit:
Actually had a brief look and might aswell work with the rust:io one, would definetly give that a try.