To add to what Phyllis said, those 20 connects should allow you to apply for a few jobs. The jobs that tend to pay less often only cost 2 connects to apply (meaning you get 10 jobs to apply to on Upwork to see if you like the system).
I would highly recommend building your profile first, having some previously linked work in your profile and then start applying. Otherwise you simply aren't making the most of your free opportunities.
I asked this because I depleted my first 20 connects, and went to top-up more, but then i saw there was this Freelance Plus thing, with premium features. Was just wondering if there's a free trial, cause i'm planning to start working quite a lot.
Anyway, thanks for the answers.