What does it mean to review campaigns and be a campaign manager? Intuitively, it seems like both require you to have joined an active Signature Campaign first.
To join a review campaign or become a campaign manager, you are not required to join a signature campaign first, as those are separate things. You can see some review campaigns on the
Bounties (Altcoins) board, even newbies also participated there. The hard part is being a campaign manager in my opinion, it's a professional field, you need to have a good portfolio & be trusted to go there.