Thanks for your interest in Zeebe. Zeebe does currently not support multi-instance subprocesses. In general, the BPMN feature set is still very limited as we are currently focus on other parts of the system (=> stability when running Zeebe in a cluster). The currently supported elements are:
- None start event
- None end event
- Sequence flow with conditions
- Service task
- Exclusive gateway
Note that Zeebe is not yet in a production-ready state, so if you starting a process automation project right now, Camunda BPM is a more robust and feature-rich choice.