Trying to install on WordPress 4.4.1

I get this error message any help would be great
Could not copy file. postman-smtp/Postman/Postman-Mail/sendgrid-php-3.2.0/vendor/guzzle/guzzle/src/Guzzle/Service/Command/LocationVisitor/Response/ResponseVisitorInterface.php

https://ww.wp.xz.cn/plugins/postman-smtp/