There is a maximum file size for uploads here on the site, but I don't think that Greenfoot on your computer limits the size. And here on the site, it is (probably) impossible to interact with other scenarios.
Greenfoot is actually limiting size. Java heab space error. Dont know what to do about it. I tried everything to minimize the size of it, still if I combine everything I get the error.
A Java heap space error means that there is probably a (small) logical error in your code (which you didn't notice). It's nothing to do with Greenfoot. It can come if you have too many actors in your World at once or something like that.
Okay, that has nothing to with the size of your project. Maybe you are creating many images or huge images or you are creating tons of actors or... well you get the point.
java.lang.OutOfMemoryError: Java heap space
That only happens if i have f.e. too many pictures in my image folder. Even if there is just a black background, no actors etc.