Google calendar syncro & add booking button

Hello,
I bought the Dokan pro plugin, it works very well thank you, but I have some problems:
1- First, in google calendar syncro, I want all my vendors to have a sync with their google calendar so they can see the bookings in their google calendar. I tried the process but it doesn’t work.
2- Secondly, I have a problem with the “Add Booking” button in the vendor’s dashboard, indeed if the vendor adds a reservation himself, it is assigned for him (in his account) and not for the customer he entered.

Looking forward to your help,
Thank you