Mailchimp plugin gets my site Vulnerable

Hi there,

I ran a scan with SiteLock and found many vulnerabilities.
I've just installed Mailchimp Integration adding newsletter subscription on my website footer. A few hours late, I've got noticed that my website is vulnerable.
How do I proceed? I probably need to remove Mailchimp plugin. But that's is one of the main reasons which I have chose wpmudev.
SiteLock sent a notification that I should pay $300 for one time adjust or $99 monthly to solve that issue.