The Scrum checklist is a simple tool to help you get started with Scrum, or assess your current implementation of Scrum.
Note that these aren't rules. They are guidelines. A team of 2 people might decide to skip the daily Scrum, since they are pair programming all day anyway and might not need a separate meeting to synchronize. Fine. Then they have intentionally skipped a Scrum practice but ensured that the underlying purpose of the scrum practice has been fulfilled in another way. That is what counts!
If you are doing Scrum it might be interesting to have the team go through this list at a retrospective. As a discussion tool, not an evaluation tool.