After exported, open the exported folder, and you must change jquery version on this folder, not your c2 installed program.
1. You can change jquery file if you can download the file version 3.4.1.
2. If dont, you can open v 3.4.1 code inside, copy and paste in your v 2.1.1, dont forget to rename the version. The code must be like this:
3. After that, open your index.html with editor, change jquery version inside this index.html target
Black screen if you forget to change in index.html