Hi,
You need to have an Azure subscription to complete the exercise. One option would be to sign up for Azure Free Trial. Once you have an Azure subscription you would sign-in using your account instead of using username/password on Resources tab (since there is no resources tab anymore).
Previously, to complete the exercise you would connect to a pre-configured lab VM, and inside of this VM it would have Resources tab with username/password that would allow you to access a temporary Azure subscription. This lab VM hasn't been available for months.
When you have completed an exercise it is important to delete any Azure resources that you created in order to keep charges to a minimum.
Please click Accept Answer and upvote if the above was useful.
Thanks.
-TP