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Custom Forms for Contacts are used to create new contacts
If you create contacts using the Integrations App, your organisation needs to use Custom Forms for Contacts rather than classic Contact Forms
Get started with Custom Forms for Contacts in 4 steps
Turn on Custom Forms for Contacts (so that your organisation has permission to use Custom Forms)
Create a Custom Form for Contacts (unlike classic Contact Forms, you need to create your first Custom Form)
Now you can use a Custom Form to create a contact in that project