Hey there, Rmack1. Welcome to the Community.
It's important to note that support for QuickBooks Desktop Pro 2015 ended several years ago, and as of October 2023, this version is no longer compatible with Intuit’s activation servers. This is the reason you're encountering an error when attempting to register the software on your new PC.
Unfortunately, older versions of QuickBooks like QBDT 2015 may not be able to be activated or fully functional due to discontinued support. We suggest upgrading to a supported version of QuickBooks to ensure compatibility, security, and access to reliable customer support.
If you have any further questions or require additional assistance, please add a comment below. We are here to help.