If you get the Are you sure you want to do this? message after uploading the theme’s zip file via Appearance > Themes menu in your WordPress, it means that your server has low upload limits.

You may go around this problem in two ways:

  1. Install the theme using an FTP. The process is described in the Installing theme article.
  2. Increase the upload limits on your server, described below.

Below are the recommended values for specific options in your server configuration:

  • max_execution_time 300
  • memory_limit 256M
  • post_max_size 128M
  • upload_max_filesize 128M

If you are not familiar how to change those values in your php.ini file then please contact your host/server provider about it. They should change them in an instant.