Teamwork is a most flexible server software: it's in Java, and runs on any database. So you can install it on any server, be it internal, your web server, or even just on your PC or Mac laptop. Being a web based application, only one installation is needed to use it from any browser of all your network. You'll have a 30 days free trial, which can be extended if needed;data inserted in the trial period will not be lost once you enter the final license. Where is the install documentation? Here.
What about sources?
Teamwork sources are under a commercial license, but also are no secret, actually we are very happy to share them for any integration purpose. Download sources of persistent classes from Sourceforge under GPL. Complete sources, inclusive of business logic are freely available for customers who sign a non-disclosure agreement, which will be send on demand. See this page for more details and links.
What about using it online, and avoiding setup, installation and all the bother?
An online service is available here. But most companies don't like to have data out of their complete control, and we understand that, so we support an installation on your machines. Moreover, a local installation is faster, gives you direct access to data, and most of all can be integrated with your local files and services.