How to use BIM 360 for free?

I'm curious to know, how can one go about using BIM 360 for free? Is there a specific process or set of steps that need to be followed in order to access its features without incurring any costs? Are there any limitations or restrictions that come with using the free version of BIM 360? Additionally, is there a way to upgrade to a paid plan if the need arises, and what are the benefits of doing so? It would be great if you could provide a clear and concise explanation of the process.