What a sandbox is
A sandbox is a separate subdomain and database that mirrors your customer production environment for testing. It only includes the product tools your organization already has on a 14 day free trial or a paid import and edit seat.
Example: if your workspace is johnsinsurancecorp.teluul.com, a sandbox named claims-test becomes something like claims-test-johnsinsurancecorp.teluul.com. Sandbox subdomain naming follows the same style of rules
used when you first signed up for your org subdomain.
How many sandboxes you can create
You can create one sandbox per paying user. During a 14 day trial, that user counts as paying for this purpose and can create one sandbox for the trial.
That only sets how many sandboxes you may create — not what is inside them. If 50 people pay for the same single tool, you can create 50 sandboxes, but each sandbox only includes that paid (or trial) tool.
Need another sandbox for the same person? See Sandbox Billing.