Don't see the page sizer menu on google docs in Safari

[drcaf]

Possibly page sizer was never meant to run in Safari -- we're running Safari version 12.03 (14606.4.5) on Mojave 10.14.13. I download, install & manage pagesizer from within Google Docs, not the Chrome Store. Nowhere can I see the page sizer menu referred to in the documentation. Perhaps I need to be running it in Chrome, and install it from the Chrome store, not the Google Docs Add-ons manager? Let me know. Thanks.