Marketing subscription through wix booking

Question:
Hello,
I’d like to add a checkbox in my booking module for subscribe to mail marketing (newsletter)
I was told i can’t do it directly in the form, so i’d like to use an automation to run velo code to do it.

I checked the documentation and tried different approaches, but i always got errors
I’m trying
import { marketingSubscriptions } from ‘wix-marketing-backend’;

To use the function:
marketingSubscriptions.subscribeContact

But the editor keeps saying
Module ‘“wix-marketing-backend”’ has no exported member 'marketingSubscriptions '.