The reason why you cannot download the .wpress file directly from the download button is that your server does not support .wpress file type.
You may need to either;
- add this line AddType application/octet-stream .wpress in to your .htaccess file. Alternatively, contact your hosting provider and get them to add mime type application/octet-stream for you in your web server configuration
- download the .wpress file that you have exported via FTP from wp-content/ai1wm-backups