From your screenshot, remove ?> */ near the bottom of that file.
And make sure that file is located at /wp-admin/content/plugins/
It’s optional but generally recommended to put it in its own folder with the same name as the plugin file. For example:
/wp-admin/content/plugins/my-plugin/my-plugin.php
but
/wp-admin/content/plugins/my-plugin.php will also work
P.S. Since it’s in the PHP comments it won’t hurt/break anything, but the Author URI line should be a link, not words plus a link.
I bet it’ll work for you this time! 🙂