Hi, I have the same problem. Easter0.zip couldn't be uploaded because it is not a valid file type. Learn more about submission
Assuming your file meets all of the required specifications I recommend you try uploading via ftp instead of the web uploader. It seems there are some unique cases in which the zip folder cannot be submitted through the web uploader. I haven't been able to source the cause yet though we are looking into it.
Thank you very much, downloading through FTP works.