Error retrieving unposted Invoices: ConnectWise 'GetUnpostedInvoices' returned an error: Username is a required field.
This error relates to the ConnectWise Member ID not being set for the user account which is currently trying to Sync records from ConnectWise.
Refer to the following KB Article to ensure that you have setup your Wise-Sync user account correctly, specifically that the ConnectWise Member ID has been provided.
KB > https://cw.wise-sync.com/support/solutions/articles/36000041650