WordPress themes are packaged in a .zip file format (not .rar). Theme Forest packages their items a little differently.
You likely need to decompress the .rar file (double-click on it). Inside will probably be another file called, vestate.zip. Try to upload that instead.
Also, in the future, support for this product should be handled via their designated channel.
http://themeforest.net/item/vestate-real-estate-wp-theme/5409523/support