Can't find macOS Mojave 10.14 download in app store

I'm currently using macOS High Sierra 10.13.6 (which was downloaded via app store). But now I can't find macOS Mojave 10.14 download in app store, and the website that should jump to the macOS Mojave 10.14 app store download page in "How to get old versions of macOS" can't be found.

The computer I'm using now is MacBook Pro (2016). How can I upgrade to macOS Mojave 10.14? Thanks a lot!