Unfortunately, it is too bad you didn’t check out the forum before purchasing. That add-on in particular has had a poor track record the past year or two.
There could be a few reasons that RCP isn’t working on your published site. It’s hard to tell without more info (and I haven’t used it in a while either).
I honestly wouldn’t count on a refund and, if it’s feasible, I’d consider another option. Ecwid has a new Rapidweaver plugin (that is free) and they have a free plan if your store is limited. There are others but that is a potentially free option for you.
cc: @dan and @bon As noted in this thread, RCP is still prominent on the community site (it’s on the front page of add-ons for me right now) and a fair number of inquiries about it on the forum lately…