If you are installing your theme from the WordPress theme installer, but get a message that says Are you sure you want to do this?, most likely your web server is configured with low PHP settings that only allow a certain size ZIP file to be uploaded via WP admin.
Most hosting companies configure their servers to only have the maximum file upload size limit at 8-10 MB, some are less. So if you get this error, your web server is rejecting the upload due to the overall size of the Boo.zip file. WordPress is, unfortunately, giving you a rather ambiguous message in response. This is not a theme issue or bug.
There two ways to solve this problem.
- You can get your web host to increase your PHP limits so a larger zip file is allowed to be uploaded. They will know which limits to set if you explain the issue.
- You can upload your theme via FTP. Please unzip the boo.zip and upload the folder inside the wp-content/themes folder.