Thanks for the logins to your site. I have checked your issue and found that the issue is caused by the child theme because when I enable the parent theme the issues you mentioned do not appear on the site after enabling the MailChimp plugin.
Now, to know how to solve your issues please watch this complete video for a better reference: https://streamable.com/2b6i9h
Note: Please watch the complete video and follow the instructions carefully.
Regards 8Themes Team.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.