First, did you follow the quick start guide and add at least one recommendation panel to your store theme?
If you followed the guide, is the theme with Recommendify enabled active on your store? Click here to see how to publish a theme.
If you've added a panel and the theme is published, it's possible that you added the code somewhere that makes it invisible. Try moving it around to different places, like right on top of the product. (This experimentation can be result in some ugly pages temporarily, so it might be a good idea to duplicate your theme and experiment on an unpublished one.)
If you tried all that and you still can't see any recommendations, try the following link, modified to fit your store:
Replace YOUR_STORE_DOMAIN with the domain of your shop, e.g. if your shop is called www.katesclothesstore.com, then the link would be https://www.recommendifyapp.com/api/www.katesclothesstore.com/similar-products/
You should see a page that looks like this:
If it is empty, send us a message.