My MacBook is and older version and I’m having some issues with updating the software, I’ve tried installing what apple support told me to and still nothing works. It keeps saying error code 102 or upgrade to latest version but it won’t

Without knowing what model MacBook you own and what the MacOS version is running on it, it appears what you want to purchase is not compatible with your older device.

Tap the little Apple at the top left on your device, then About this Mac and let us know the model and version.

You need to have a more recent version of the Mac App Store installed to make progress. Use the links in this article to install exactly this version: MacOS 10.11 El Capitan -- as a waypoint,

because it contains the modern Mac App Store and can allow you to move to a more modern version.

How to get old versions of macOS - Apple Support

From what I've been able to read, your MBP can be updated to MacOS 10.15.x.

And it appears the app you want to purchase requires at least that version. So, what is happening when you try to update your Mac? Do you have any Antivirus/Cleanup/VPN 3rd party tools on your Mac? If you do, remove them. They are notorious for causing issues and could be preventing you from updating.

If you simply can't get your MBP updated, schedule an appointment at your Apple Store Genius Bar and let them help you update it.