I have purchased about a dozen actions from this site. Most work OK, but a few have not worked from the get go. Others work initially, but don’t after a PS update. In each case where an action fails I contact the author directly. Thus far, I have yet to have the issues I’ve run into resolved. I even contacted an author prior to buying an action to make sure it would be compatible with PS CC 2017, and never heard back.
I appreciate the work that goes into creating these actions. I wouldn’t begin to know how to even start to make one myself, and I like that people have the means to market what they do. However, if the author does nothing for the buyer after the sale, what’s the point? If you’re going to create something & try to sell it, you should make sure it will work for all versions of PS, and respond to emails sent by your customers!