What feels like forever now, you could visit the Instructure main Canvas page and sign up for a 14-day trial-instance of Canvas. It would auto generate a Canvas instance, and provide you with admin access to https://[name-generated-based-on-company-name-filled-in-on-form].acme.instructure.com/ (which is where the 'acme' comes from).
That service is no longer provided as of 2018/2019, so the OP must have been looking at very old posts, and you now simply have to create a Free For Teacher instance @ https://www.instructure.com/canvas/try-canvas
The other option is to contact Canvas to become a partner, pay the partner license fee, and you'll get a https://[business-name]-test.instructure.com/ environment with full Admin access to develop, test, demo, and anything needed with, and contact Canvas Support for technical questions.
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