SendGrid Auto-Subscribe settings empty, component doesn't render

NOTE: The selected category is incorrect because selecting one was required and there isn't one available for the SendGrid Auto-Subscribe plugin.

Just purchased the SendGrid Auto-Subscribe plugin, but I can't access the settings page for it. The "com_sendgrid" page is just blank.

Also, as soon as I add the mod_sendgrid module to any page, that page stops rendering as well. The module settings are available, though they don't include any way to configure the sendgrid account etc to use.

(Joomla 3.4.8)