This is to continue a discussion that has been closed, so I am creating a new post:
I created a form and 'd like to add a custom field: not email, name or last name, but a text area when subscribers can add additional details about themselves. Following the recommendations above, I've tried two approaches and both failed:
1) Direct integration with Mailchimp: I created a so-called "General form" and managed to add a column for the additional field that I need to include in my list, it does appear next to the "email" column when I open the list on Mailchimp, but I can't find a way to pass the desired information from webflow into the newly-generated Mailchimp list. I tried to use name for the form elements that are coincident with the names in the mailchimp list, but it doesn't work, only the email address gets passed on
2) Integration via Zapier
Even though I would prefer approach 1 instead of adding an extra step in between, I did try to follow the steps described here: http://forum.webflow.com/t/new-feature-zapier-integration-for-form-submissions/11188
The problem is, the site name is recognised (I get a list of all my webflow sites and then select the one I am working on), but the form name is not. I have two forms on the site, none of them appears in the "form name" dropdown in the Zapier interface. If I select the option "Use a custom value", and use the same name I used for the form in webflow, I later get an error message"":
_Bargle. We hit an error fetching a form submission. Error: _
_ api.webflow.com returned (500) Internal Server Error and said "Error: Please submit a sample form submission""
I tried to make a submission on the live site but the error is still there.