@Uberseehandel In as much as anything is my specialty, getting Win10 to connect to the client VPN is it.
What happens if you try the script I linked above? You can either create a one-and-done where you prepopulate the MX/Z's address, PSK, and - if split tunnel - subnets in the 192.168.0.0/24 format. AKA, your network IP slash CIDR notation.
Or you can run the script that prompts you for address, PSK, and subnets. Please read the comments on the scripts before running them. Default setup is an AllUserConnection, but I provide instructions for making it a single user connection.
For address, either use the Meraki-provided dynamic DNS (check the client VPN page) or create a CNAME record that points to that name. This way, you don't have to reconfigure end users if you change ISPs or failover between WAN1 and WAN2.