To connect your WordPress site to MailUp you need to enter the address of your console in the plugin settings (Console URL).
To get it, just log in to MailUp with your credentials and look at the web page address, it could look like this:
https://b4e5d8.emailsp.com/console/Main.aspx#/main
In this case, the console URL to be entered in the plugin settings would be as follows:
https://b4e5d8.emailsp.com/

Also make sure that web services are active in you MailUp settings:
