Apparently, Aseprite is not open source, so I'm not sure how you can "compile it yourself" - compared to Gimp for example.
Also, please stop talking about trying to "crack" a software in our forums.
As previously mentioned, why not supporting a solo-developer who has put hours of work in a product you are looking to use ?
Piracy talks won't be tolerated in those forums.
At last Construct does have some basic drawing tools that may help you get started and already do prototype graphics to start prototyping your games.