Hello there, La Redemption.
Only QuickBooks for Mac 2016 or later is supported by Mojave. You'll want to upgrade to the latest MAC version so you can work on that operating system. You can check this article about system requirements (QuickBooks for Mac): QuickBooks Desktop system requirements.
Visit our website to purchase a new software: https://quickbooks.intuit.com/desktop/mac/.
Don't hesitate to reach out to us if you have other concerns. Happy New Year!