That's very strange that it couldn't find the file from your install page - have you tried it since? We haven't had any issues getting it thus far. Per-product reviews are coming very soon - we wanted to get this "overall" plugin working and in the wild before adding too many of our most-wanted features. If I may copy-paste a response from a similar thread:
Right now this plugin only allows for site-wide reviews, rather than per-page or per-product reviews. However, in the list of upcoming features, per-product reviews is extremely high (and relatively painless to implement, too!). Expect to see this feature within a week or two, at the latest.