ZOHO writer mail merge: only works for 1 user, not for the others

ZOHO writer mail merge: only works for 1 user, not for the others

We created a template for mail merge in Zoho Writer. It works fine for 1 user. However, it doesn't work for the other 4 users: the mail doesn't fetch the CRM data and gives and error message. All users have the same rights, use the same browser. Someone any idea what's happening?