The column Product access shows you which products your employees can access. If you started in Zenegy Payroll and have added Zenegy Expense, your employee's access to Expense is deactivated as default. So if you want them to have access, you need to add access rights to their employee profiles.
Go to Organization > Employees > column Product access > column Expense. Move the toggle to the right to activate the employee/s access to Zenegy Expense.
Please bear in mind that turning on product access has an additional cost.