Right now, the free download is very hard to figure out. It isn't clear that the price input expects the user to write a value in it, nor that there is a minimum value. I would recommend using the placeholder value as the value if the user doesn't enter anything. Additionally, the call to action is very ambiguous. "I want this!" doesn't really tell me what's going to happen when I click it. What if I'm curious and I don't really know if I want this? Etc. Plain old "Buy" or "Download" are universally known and understood.