If you make use only of the accounting and group structure provided by default, all you need is a standard Cyclos installation.
However, Cyclos is quite a complex but powerful software. Be aware that the installation of a default Cyclos instance may be quite easy, but the configuration of the software to meet your business requirements may not. It will be particularly time-costing if you need to tweak the accounting and/or group structure provided by default.
In Cyclos Wiki you can find extensive info about the business rules:
If your project is complex, it is highly advisable that you have in your team at least a person who understands profusely both the Cyclos administration and your business requirements.