John's response is correct if what you are really looking for is a field. You would use the DocProperty field. That may give you what you need. If so, you should mark his response as Answering your question to help future users of this forum.
The following may be more complex than you care to get into.
You may be looking, instead, to insert the Company Document Property Content Control. The user interface on the Mac does not support doing this.
The XML node for such a Content Control exists in .docx documents created in Word, whether on the Mac, PC, or online, so long as created in Word. So the controls work in a document on a Mac.
The simplest way to insert such a mapped Content Control into your document on the Mac is to get a document containing it that was created on a PC (Windows) and copy the Content Control into your Mac document.
I've posted a macro-free template with the 15 built-in mapped Document Property Content Controls on my website. You can download it from there. https://addbalance.com/word/DocumentPropertyContentControlsMac.dotx The template can be put in your Startup folder if you want. These are saved as an AutoText entry in the template and if placed in your Startup folder, the AutoText with the Document Property Content Controls would be available in any document.