HELP: Asus Lyra MAP-AC2200 Mesh install issue

When following the instructions here, I am able to upload the .itb file via ssh and run the install command given, the reboot -f, but after I upload the .bin file and try the sysupgrade step, I get an error saying sysupgrade: not found

Are the instructions missing a step, or am I misunderstanding something here? Any help is greatly appreciated.