Yes, this is my MX configuration for zscaler tunnel with meraki.
under non Meraki section enter the name for your zscaler node and the public ip of your zscaler node.now the ipsec custom policies i have configured like below.
Now you have to whitelist your MX wan ip with zscaler by raising a ticket with them.
and then you need to configure the VPN credentials at Zscaler for your MX WAN ip. Make sure it matches with meraki also.
Now add location at zscaler and call your vpn credentials and add your private ip's range as sub location.