synch with bill.com

I recently upgraded from Quickbooks for Non-profits 2021 to Quickbooks Pro Plus 2024. After the upgrade, the synch will bill.com was working intermittently. When I called bill.com support for help, the support desk advised me to delete bill.com from the integrated applications under preferences>integrated applications and the reinstall the synch dashboard. I spent quite awhile on the phone with bill.com support trying to get the synch to work (open their synch dashboard, then open Quickbooks, then allow changes on the drive). The error I receive every time says 'Open the Quickbooks company file and synch again.' I do notice that there is still no bill.com option under integrated applications and I think this could be part of the problem. I cannot find any instructions on how to add bill.com as an integrated application in Quickbooks.