Unable to add the extension to Ultimate Member

Hello,

I have bought the MailChimp extension through the Ultimate Member plug-in page. And have followed the instructions showed on: https://docs.ultimatemember.com/article/82-mailchimp-setup#extra_settings

However, theres no 'Extensions' section for me to add the API key to Ultimate Member in www.remarpro.com, and I couldnt find any other way to integrate both.

The page I need help with: [log in to see the link]