To embed an Adventr on a Wix site, you need to add an "HTML EMBED" section.

From there you have a couple options to experiment with by switching between Embed Types.

You can paste your Adventr's embed code in the HTML Code option like this:

The advantage of this approach is that it's incredibly easy. However, you have less control over the size of the Adventr embed. 

Or you can switch to the Website embed type, and paste in the url contained in src="" in your Adventr embed code.

This approach is a more advanced (you have to copy the URL out of the src part of the iframe embed code), but then it allows you to use the width and height controls provided by Wix to customize your embed.