Artist in Need of Help

Hi! Sorry for not being active. It's still school and life that keeps me busy. Anyways, i have a problem. Recently I was working on a comic, and other art trades and artworks, on Medibang (on my iPad) but Medibang keeps exiting me out! Most of the time, not saving my art progress, making it a waste of time trying to redraw, and ending up kicked out! I try to fix the situation checking if it's my iPad or the app, and the thing is i love using Medibang, it's the only art program i used for all my digital artworks. So can someone please help by recommending me what art app i should use (free, nothing that costs money) and that is similar to Medibang? It would be a big help!