When saving your project, select "Save as single file" to get a .capx. You have attached a .rar file of your project files.
The .capx is basically just an archive of your project (like .rar), but we can open it directly in C2 without having to extract the archive and cluttering our folders with a bunch of project files.
Please upload a .capx, and I'll have a look to see if I can help you.