You might want to get a more experienced developer look at your code.
Thanks for your advice and for trying to help me. I will do that if I find someone. If it's ok I do have one last question. What is the max size of the project that I can upload to Itch if I decide to go with "Downloadable" option?
The limit is 1GB by default, two if you use Butler. You can also contact support and ask for an increase if that's not enough.