I have pasted in the header of the page inspector and tried the General header for the site
This code allows ManyChat to display opt-in forms on your website and track subscriber activity. Install it just once per website and have unlimited fun with our widgets!
Is there another piece of code? Often, things like this will give you a piece of code to put in the ‘head’ section and another to put on your page where you want the widget to appear (which you’d put in an html stack, and ensure to ignore formatting).
For this to work in RW preview, you will likely need to prefix the SRC attribute value http:// or https://. RW7 only whitelists certain domains like Google, YouTube, Vimeo, Facebook etc. The rest of the time you need to add the proper protocol yourself.