My understanding is that the "authors" get paid for "upvotes", so yes, the users have to be signed in and click some button or something. New users get some free upvotes but apparently the idea is that eventually they'll need to pay (once the premine runs out?).
Nobody ever has to pay, at least not for many years when the business model could change. The upvotes don't "run out" (they do recharge if depleted by overuse over five days, at no cost).
Steemit is a blogging and discussion platform. The there are certainly low quality links to crap, and those should be evaluated on substance (or lack thereof), but most of the links are just links to people's biog posts or discussion, the same as medium, reddit, etc.