The issue might be because of AeonFree's Upload limit of 10 MB. Can you check if the file is larger than 10 MB?
As Wordpress.com only allows backups through XML you cannot manually backup all the files.
What you can do is, you can install your own server (XAMPP or any other localhost server) on your PC, install WordPress, and then manually backup all the files from your PC to Aeonfree. If you don't want to do this hassle, then you should probably consider premium hosting.
If you need any help regarding the migration, I will be there to guide you. Just drop your message in this forum post.
Regards!