Is it legal if i post a mod on curese

Of course it is :) Go right on ahead

Just don't try to make people pay money for your mod. THAT isn't legal.

There is one thing you have to keep in mind. You have to mention that the mod has been created using MCreator.

Yep it's totally find as long as you mention it was made with MCreator, although I personally wouldn't as most other modders seem to hate MCreator, and you don't want comments full of that. In fact, is it just me, or does the Any Dimension Mod not credit MCreator?? https://www.curseforge.com/minecraft/mc-mods/any-dimension-mod-1-7-10 See for yourself.

Hello! I understand your concern but I did actually credit MCreator back in 2015.

It's at the bottom of the mod description, right below the "Install" section. It's always been there, see for yourself ^^

Have a nice day :)