In the Backup .Zip File
The expected location of
importbuddy.php inside the actual backup at
/wp-content/uploads/backupbuddy_temp/xxxxxx/ where the
xxxxxx will be a folder with the serial code name that matches the one in the name of the backup. You will need to extract the backup archive in order to obtain this importbuddy.php file.
Since importbuddy.php files aren't connected to any specific site or backup file, you can use an importbuddy.php script from any site (as long as you know the password connected to that other site's ImportBuddy). You can find other ways to recover the ImportBuddy script, and set a new password in this article.
In the Plugin
The importbuddy.php script can also be found within the BackupBuddy plugin itself by heading over to BackupBuddy > Backups to find it in the top-right of the page.
In the Sync Dashboard
The importbuddy.php script can also be found within the Sync Dashboard. Once a site has been added to Sync you can then select the site from the Home tab in the Sync Dashboard and then navigate to the BackupBuddy view.