According to their web site here:
https://autodessys.com/formz_comparison/

It says that "Unfold model with tabs and labels" (under Product Design) is in the pro version, not in the free version.

Also I seem to remember it's not really for sheet metal, it's for papercraft type stuff like Pepakura Designer.

EDIT:
https://s3.us-east-2.amazonaws.com/assets.autodessys.com/manuals/formz10/formZ_Pro/responsive_html/10146_Unfold.html

Looks like it can do also NURBS unfolded as NURBS when there are developable surfaces. So that might work ok (in pro version) for sheet metal models too. For polygon mesh objects it does Pepakura Designer type stuff with making tabs.

- Michael