Need Help creating site to site VPN between a cisco router and a Stormshield firewall

Hi there fine people,

I am trying to set up a VPN between a Cisco C1117 LTE and a Stormshield SN510.
Unfortunatly i havent touched a Cisco appliance in many years, and some details of the configuration are escaping my logic. I'm trying to use the Web UI for the VPN setup.

For instance, on the Cisco router I have to create a Tunnel interface with it's own IP address. Where does this address get used in the SN VPN configuration ?

I'm aware informations must be lacking to answer correctly but I'm not sure of what's relevant or not... Thanks in advance for your help !