OrgStruct is gone in org-mode 9.2. I guess this applies to the ELPA package version you mention as well.
Removal of OrgStruct mode mode and radio lists
OrgStruct minor mode and radio lists mechanism (org-list-send-list and org-list-radio-lists-templates) are removed from the code base.
Note that only radio lists have been removed, not radio tables.
If you want to manipulate lists like in Org in other modes, we suggest to use orgalist.el, which you can install from GNU ELPA.
If you want to use Org folding outside of Org buffers, you can have a look at the outshine package in the MELPA repository.
The rationale for the removal according to this mailing list thread was basically: it was broken, hackish, made org-mode development harder, and there are alternatives.