First off, the £5 credit should be desribed as BONUS credit, never as free credit. Calling it bonus credit makes it clearer that a payment must be made before receiving the credit. Describing it as free credit gives people the wrong impression that there’s credit already on the sim, so they expect to be able to spend that credit without needing to pay anything.
Secondly, its the person activating the sim that gets the £5 bonus. Super recruiters don’t normally (except in very occasional promotions) get anything for activation, only if and when the member buys their second and third credits or goodybags.