I've done this with no issues. Set up the "Non-Meraki VPN peers" on the Meraki. Use the paramters you need. Enable the Meraki subnets you want in the tunnel and save. Then go to the Palo, create an IKE profile that matches the choices from the Meraki. Do the same for IPSec profile. Create an IKE Gateway on the Palo using the same autheneticated method, we used PSK. Create the IPSec Tunnel and use Proxy IDs to match up subnet on the Meraki to a subnet on the Palo. Just like configuring an ASA, these have to match the Palo and the Meraki. Then put in routes in the Palo router for the traffic. Finally create Security Policies to allow the tunnel to be created (outside interface to outside interface) and then a policies for the traffic to pass. Pay attention to the IKE, IPSec, PSK, subnets and Proxy IDs and you should have no trouble.
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