Shouldn't mapping CRM fields to Form-fields auto-populate or update these fields?

Shouldn't mapping CRM fields to Form-fields auto-populate or update these fields?

I have integrated ZOHO-CRM with ZOHO-Forms and I have linked/mapped every field in my Form to fields in my CRM (Leads). Also I have activated 'update info with existing Lead-contacts', but the information does not populate these before-mentioned fields! Instead a pdf-file (of the filled-in form) is added to the 'Lead'. What did I do wrong?