Zoho Campaign says "null"

Zoho Campaign says "null"

Here is what I did:
1. Created a list in CRM, made a form to fill information in the list. - This is working fine.
2. Created a flow to connect CRM (chose a the list) and want to add an event in Google Calendar. (Calendar is connected).

Problem 1 - When I am testing the flow, it says "Zoho Campaign says "null"" -- What does that supposed to mean to the end user?

Problem 2 - When adding the form to fill subscriptions to the list, i want a hidden date and time field - How do i set a default value to that field, when there is no calendar icon present and when special characters are not allowed?

Can someone let me know if I am missing anything. Screenshot below for reference.

Thank you,
Chethan.