How to fix build.ninja not found? (macOS terminal: compiling Aseprite)

Hello all! I have tried to compile ‘Aseprite’ following the instructions on this link: https://github.com/aseprite/aseprite/blob/master/INSTALL.md

The final step is to run this command in the build directory inside the aseprite directory:

ninja aseprite

Whenever I run that, I receive the following error message: 

ninja: error: loading 'build.ninja' : No such file or directory

I installed ninja through homebrew 

brew install ninja

Image attached below:

What am I doing wrong? What is happening? I really need help ASAP because I need to generate a sprite for a game, and this software is really good at making sprites. Thanks for all the help, and hope this is the right forum to post in. If not please inform me of which forum I need to post it in.  

I am having this same problem. Have you found the solution?