Need to access a Word 2016 template from a SharePoint online site

Here is my situation:

We have a Word 2016 fill-able form.

We want to store the form in a department SharePoint site with limited access but make the form available to everyone via a link on the company intranet. We also want to force the template to open in the Word 2016 client - not in Word Online.

After researching content types, I discovered that SharePoint Properties has replaced them.

I found a lot of information about using content types while creating your form. Little information on the SharePoint properties. Zero information about using a form already created.  A lot of work went into creating this Word fillable form.

Can anyone help point me in the correct direction to do what I need.

Specifically:

 1 - Have a link on the intranet to a fill-able Word 2016 form

2 - As users complete the form and save it, the resulting document should be stored in a SharePoint site with permissions for viewing/editing the form by only the site members and original creator of the form.

Any help is much appreciated.