the aws link is always yellow？ what is the problem？
If you open the lab from Coursera and the AWS link turns yellow, that’s usually normal while the environment is being provisioned. The first launch is often relatively quick. However, if you need to reopen the lab, the second and subsequent attempts can take noticeably longer.
If the link remains yellow, please wait a bit longer before trying anything else. In many cases, the environment is still starting up and will eventually become available. The second and consecutive launches often take more time than the initial one.
Let us know if it stays yellow.
OK ，the problem is solved, thanks