I think you're a bit confused by versions.
Are you trying to upload an AI Classic zip file into AI2?
Only an AI2 aia file can be imported into AppInventor 2. If you have a project you did with AI Classic, you'll have to redo it in AI2 to use AI2. If this is the case, you can still use the AI Classic for the next few months, after which it'll be retired.
There is NO zip folder downloaded for AI2, only for AI Classic. AI2 uses aia files, not zip files.
What version of file are you trying to import?
You wrote:

But
there is no .aia file inside the zip folder which is downlaod from MIT
App inventor. so i couldn't upload the project at all.