The first requirement is to have Meraki AutoVPN enabled in all your sites.
Then in Security & SD-WAN > Site-to-site VPN of the network where you have setup the static route, you will see that destination subnet listed in the Local Networks.
When you change the dropdown from "no" to "yes" for that entry, it will be announced inside the AutoVPN network. Now your other sites will be able to use the static route going through Meraki AutoVPN.