Something went wrong. Cannot access private property Idno\Core\Idno::$config

I input the key and secret and am presenting with
"Something went wrong. Cannot access private property Idno\Core\Idno::$config"

How can I rectify this issue?

Thank you.

[timmmmyboy]

This plugin was built 5 years ago. I wouldn't be surprised if either Known or the Tumblr API (or likely both) have changed significantly in that time. I don't do any development for Known anymore so if this plugin is something someone wants to take on happy to pass it on to them, but I won't be supporting it.