What's up, Bro
First of all, great you apply, second what I say means nothing because I am not a spriter myself, but, I recommend contributing to github before making a spriter application, if you dont have work to show off. It's probably hard to judge the quality of your work if you can't show something off. So I recommend either doing some stuff and posting it here or working on the github and making new sprites for whatever you want and be a contributer to the github first.
Still, great that you apply and want to help out.