The fact that she's giving this away for free is pretty amazing. The people complaining don't realize that the plugin does work flawlessly, you just might have to make one very minor edit to make it work for your specific template. The issue I was dealing with specifically was because I had a crappy template author.
I installed the plugin and it wasn't working completely. I purchased the additional plugin Stripe+ (More) because I needed recurring billing for what I'm doing. She worked with me to set-up the Stripe+ (More) plugin and to get this free plugin working for my theme.
She can only control what she can control. If you're having issues because your template was written terribly - simply pay the very minor amount to get support help - or purchase Stripe+ (More) if you need recurring payments.