First off, make sure Zahara is connected to Xero in Business Settings > Integrations. Clicking Synchronise is a good way to test the connection is all good.
Next, enable importing of invoices from Xero – (make sure your export Invoice settings isn’t set to Draft)
As shown above, you need to select a Division and a default nominal code. One of the things Zahara has that Xero doesn’t, is Divisions so you need to set a default Division. In fact, you could create a separate Division specifically for these invoices that follows a specific approval process. Invoices can also land in Draft in Xero with key bits of information missing like Tax Rates and Nominal Codes. The default nominal code here is a fallback code for Zahara to use if the coding is missing. Zahara will flag up any missing or rogue entries.
Creating an approval workflow with a coding step is recommended.