Electronic case book sought for a public administration (for approx. 100-200 users)

We are looking for an electronic transaction log for a large city to record and process incoming invoices. The transaction log should record all transactions that have an accounting impact, such as incoming invoices (accounts payable), but also outgoing invoices (accounts receivable), notices, internal transfers or offsets, etc., regardless of data formats.

Our rough ideas for the software are:

• Web application
• Recording of all incoming invoices (accounts payable) (scanned or as e-invoices)
• Extendable to outgoing invoices (accounts receivable)
• Organization of a self-configurable process workflow with respective status documentation
• Communication with interfaces (DMS; ERP system OK.FIS; if necessary, official specialist procedures (e.g., OpenProsoz; IMS))
• Digital approval workflow (in accordance with official budgetary law: e.g., dual control principle, audit and transaction security)
• User and role management compatible with MS Windows Active Directory
• Multi-client capability to enable possible future expansions, e.g., different ERP systems of the city's subsidiaries

Approximately 100-200 software workstations are planned.