Greetings, TT123g.
I see that you're unable to upgrade your MacBook Pro to macOS Mojave. It appears to start to download, but then nothing happens. I'm happy to help.
How to upgrade to macOS Mojave -- See if the macOS Mojave installer is located in your Applications folder. If it is, you can use that. Or, you can delete it and download a fresh copy. If you can't locate the installer, this article provides the information and steps that you need. Be sure to check everything under "Check compatibility".
How to reset the System Management Controller (SMC) on your Mac -- If the installer wasn't present or you still can't download it, reset the System Management Controller. Follow the steps under "How to reset the SMC on Mac notebooks" for a nonremovable battery. Test the issue once you're back to the desktop.
If you're using a 2018 MacBook Pro that uses the T2 chip, follow the steps under How to reset the SMC on a Mac that has the Apple T2 chip
Use safe mode to isolate issues with your Mac -- If you're still unable to upgrade your Mac restart your Mac in safe mode and see if you can install it from there. Afterwards, reboot normally and log into your own user account. Remember this when booting in safe mode: Graphics performance limited in macOS Recovery, safe mode, or Guest User mode
Let me know how that goes, and take care!