If the creators read this, I suggest some ways of building trust. There’s no “about us”, no GitHub link, etc. It’s a random webpage that wants my personal details, and sends me a “exe”. The overlap of people who understand what this tool does, and people who would run that “exe” is pretty small.
I have just added a bit of info about us on the website. I'm not sure what else we can do really. Its a trust thing, same with any software and AV vendors.
When someone is offering you a certificate and the only thing you have to do in order to get it is pay them a significant amount of money, that's a major red flag that it's either a scam or you're being extorted. Or both. In any case you should not pay them and neither should anyone else.