Ok the 10.14.1 you downloaded is an update to macOS Mojave and to install that you would already need to be
using an earlier version of macOS Mojave.
The next thing you need to know is to upgrade your operating system you need to download the full installer
app via the App Store.
Apple removes the previous full installer app from the App Store when a new incremental update gets released.
When Mojave first came out it was version 10.14.0, when Apple updated this to version 10.14.1
they pulled the 10.14.0 version of the full installer in favour of 10.14.1, this pattern repeats until the last full version
of macOS Mojave which is available 10.14.6.
All you need to do is download this full version installer app.
Open Safari and click on this link,
How to get old versions of macOS – Apple Support
Go to Check Compatibility to see if your mac qualifies for macOS Mojave.
Then go to the Download OS section and click on macOS Mojave.
This will redirect you to the App Store Mojave download page,
it should say Get or Download.
This will download the full version installer for macOS Mojave called
Install macOS Mojave.app and will install a full working
version of macOS Mojave 10.14.6, you do not need 10.14.0 it no longer exists or
any other updates you may have downloaded from the Apple Support Downloads site.
The installer app is 6.2GBs in size.
Double-clicking on it will start the installation process.
Before upgrading make a full back up of your Mac.
Check that third party apps you use have updates available for the new OS.
https://roaringapps.com
Check that your printers/ scanners etc have updated drivers and software available for the new OS.
Connect your mac to your router via cable rather than rely on WiFi.
Do not use your mac while it is downloading
and do not use any other devices that share the same internet connection.
If the App Store says ‘Open’ then it is detecting a previous download of the install app
go to the Applications folder locate Install macOS Mojave.app.
Move it to the Trash, empty the Trash.
Restart, click on the link again, the App Store should say ‘Get' or 'Download'.
