I'm only seeing a Windows build on the website. Doesn't help OP much when they have a phone: "Please especially in third-world, we have so poor phones."

I don't know if you've been to Africa, but PCs are not common there unless you're working in a company. Depending on where you are, a small portion of the population has personal laptops. Otherwise feature phones or smartphones are the best people have. So linking to a Windows-only application for someone who lives in a developing country and only lists a cellphone may not be very applicable to them.