Can’t link button and popup

I am trying to link a mailmunch popup — short code -#mailmunch-pop-552742
and a max button —- code —[maxbutton id=”2″][maxbutton name=”Free Ebook Download”]
to place in a widget for the sidebar. I have read it can be done, but I am not great with coding and when I do try it, it is not working.
What is the correct code format to link these and will it work in the custom HTML widget or should I use a different one. I do have mailchimp too. Thank you.