Get fbclid from URL

According to the instructions provided in Facebook Conversions API plugin by Drive Phase Consulting:

You can do so with a Get data from page URL WHEN Page is loaded and save the parameter “fbclid” as a custom state.

Would this be the correct way to do it?

My error is:

Unfortunately, I’m unable to copy & paste the error; hence the image above.

I’ve reached out to the author, but I thought of posting it here as well in case anyone could help me & so that others could refer.