Institute seeks accounting software

We are a psychological institute and are looking for accounting software - for financial reporting in the broadest sense.

The solution should meet the following requirements:

• Financial accounting (balance sheet, income statement)
• Accounts receivable accounting (especially invoicing and dunning, management of installment agreements, etc.)
• Accounts payable (on a very small scale and only of secondary importance)
• If possible, we would also like to include customer management
• Windows compatible

Two to three people should be able to work with the software.