Yes. Put simply, any business operation which pays tax must have a Tax File Number (TFN). A TFN is your identifier with the the ATO.
You can apply for a TFN when completing the ABN application for your trust, it's as simple as electronically ticking a box! Otherwise you can apply for one directly through the ATO at a later stage but you should have a TFN registered prior to the commencement of business activities.