The OpenWRT pacakge is not built or maintained by ZeroTier Inc.
https://github.com/mwarning/zerotier-openwrt/
See their wiki for instructions for routing between your ZeroTier network and physical LAN via OpenWRT
https://github.com/mwarning/zerotier-openwrt/wiki
Also not a package built or maintained by ZeroTier.
https://docs.opnsense.org/manual/how-tos/zerotier.html
https://wiki.teltonika-networks.com/view/ZeroTier_Configuration