Contact from invoice are not synced to zoho crm

Contact from invoice are not synced to zoho crm

Hello

I cant find a way to sync   invoice contact and operation to zoho crm ...      link is created and well configurated . 

But in fact , contact and operation not apperas in zoho crm . 


have an idea ?

im a on the free plan , maybe its for that ?

Plz help 

Best regards