You are trying to install AvaTax and receive "Error while subscribing to QuickBooks events. Function Name = DoSubscribeEvents 80040423. The version of QBXML that was requested is not supported or is unknown. Please login using Administrator Privileges and try again."
We have reached out to Intuit about this issue and it's mostly related to a corrupted QuickBooks Desktop installation. We suggest re-installing QuickBooks and check if the issue still persists.