May i know if you really need to do the ethernet bridging with RUTX09?
If your main goal is to have an end to end connectivity between the LAN Device of the router and the zerotier devices then it should be not a problem.
Just configure zerotier on the RUTX09 router and wait for the router to have an IP address assigned by zero tier. From that on zerotier add manage route where you will input the LAN address of the RUTX09.
192.168.100.0/24 via 192.168.192.1 -> Zerotier managed ip assigned to RUTX09
And from that you will have end to end connectivity with the zerotier on your zerotier network and the LAN network of RUTX09.
If you really want to use ether bridging. As you can see Zerotier is a 3rd party platform that is supported by our Teltonika routers regarding on how to set it up on zerotier we cannot provide support for that. Also by checking in Zerotier there are no procedure on how to implement Etherbridging
Hope it helps