There's a lot of relevant information we don't know (targeting, platform, demographics, competition, payment etc.). If your 6 signups are paying anything, I wo

There's a lot of relevant information we don't know (targeting, platform, demographics, competition, payment etc.). If your 6 signups are paying anything, I would continue iterating ads and working on the product. If those 6 signups are unpaid, and just people who signed up after viewing the site, I would stop spending and reassess the product and marketing. I'd expect only a small fraction of those people to ever pay anything, with many never returning to the site at all. Also I wouldn't focus too much on the CTR or CVR - you are getting dirt cheap (likely untargeted) visitors ($0.019/each) so you should expect low rates. What matters is your ROAS (return on ad spend). You should be tracking that obsessively.