Error activating plugin

I’m trying to activate the plugin and am getting an error:

Warning: require_once(e:\blah\wp/wp-content/plugins/wp-recaptcha/confidentcaptcha/ConfidentCaptchaCredentials.php) [function.require-once]: failed to open stream: No such file or directory in e:\blah\wp\wp-content\plugins\confident-captcha\confidentCaptcha.php on line 157

I’ve checked that the file does exist, but I suspect I need to add write permissions to something… anyone know what this error could be from?

https://wordpress.org/plugins/confident-captcha/