Error when trying to create integration

I am trying to set up an integration to Integromat – I have done:

Integromat: create a custom webhook, saved and run – copied URL

Forms To Zapier-Integrations-Add New: select CF7, select the form, pased the webhook URL and save

I get the default Integrations screen with no Integrations listed – just: Whoops, you haven’t created a relation yet. Want to give it a go?

Am I missing a step?

I also have it installed on a Multisite network – that may be relevent!

Thanks