Mojave 10.14

Sounds like you have been trying to install updates (Apple Support Downloads) to macOS Mojave, you cannot install those unless you have already installed an earlier version of Mojave. The full installer is only available through the App Store. Please read the following link, and go to Section 4 and click on Get macOS Mojave, How to upgrade to macOS Mojave - Apple Support

This will download the full installer version which is 6.05GBs and will appear in your Applications folder. The version of Mojave it installs is10.14.6. By downloading this full installer you do not need 10.14, the first version of Mojave 10.14 was replaced when 10.14.1 was introduced and this pattern is repeated by Apple with each new version release up until the last/ latest which is 10.14.6.

I have already told you that any updates, like the Combo you have downloaded from Apple Support Downloads will not install as they require you to already be running Mojave, so stop trying.

I have already told you you can only get the full installer via the App Store.

The screenshot of the App Store you have posted says 'Open' that means the App Store has detected that you have already downloaded Mojave so look for Install macOS Mojave.app in your Applications folder, if it has downloaded completely it should be 6.05GBs. If it is just double-click it to start the installation. If it is a partial download move it to the Trash, empty the Trash and download it again.

Read posts carefully before responding.

When you download Mojave is it downloading the full 6.05GBs installer.

If you are using WiFi to download try a cabled connection to your router.

If you see Install macOS Mojave.app in your Application folder and it is 6.05GBs

double-click on it to start the installation, do not go back to the App Store and click Open.