When attempting to open some MS Word Docs I'm asked to download - STHeiti and other fonts

When opening one of my documents in Word 2011 on MacOS 10.12.3, I'm asked to download a series of fonts including: STHeiti and Osaka.

I assume this means the document was opened on a computer with those fonts installed and now the file is convinced they need to exist.

I've tried accepting the downloads but the problem just returns the next time I reboot my mac.

So where should these fonts be installed and where is Office installing them?

The solution was hinted at in the comments.

1. Open FontBook:
   Launch Font Book.app (located in the Applications folder).
2. Find the fonts in question:
   Select "All fonts" in the sidebar and search for them using the search box in the upper-right corner of the window. Once found, each will be greyed out.
3. Download the font:
   Either press the "Download" button in upper-right corner of the preview pane or right-click the font to display the context menu and select "Download".
4. Smile now that MS Office doesn't ask you skip/download whenever you open that doc again.