This article presumes you have experimented with Zing on your own using the Zing free trial or otherwise have determined Zing would work with your applications, but have not yet contacted Azul.
You can directly buy small number of one year host-based licenses on the following page over Paypal: Order Zing by Credit Card
For long term licenses and larger volumes of licenses please reach out to firstname.lastname@example.org or complete the request form for generic Azul inquiries. An on-site trial is different from a self-guided trial because it typically involves you working closely with Azul to qualify Zing against your evaluation criteria. Azul wants to help you meet all your business justifications, in addition to ensuring a technical fit.
If you are an open source developer, academic researcher or other qualified participants, take a look at the Zing Open Source Developer program.
Many presales materials, Zing product datasheets, and service and support offerings are enumerated here and should provide all you need to research Zing for your use cases.
Still unsure? Email email@example.com and Azul will help figure out your needs.