Invoices can be searched from the Invoices section using various criteria through a free text field or filters.
All filtered invoices can be downloaded to the workstation at once by clicking Download filtered invoices.
In addition, all customer's invoices can be found on the customer card under the Invoices tab:
Permissions to view invoices can be shared in the user settings. If you cannot find the invoice you are looking for, check your access rights to invoices.