title: solve ResolvePackageNotFound in yml environments
body: <p>I'm trying to follow this link on my local computer</p>
  <p><a href="https://github.com/lyakaap/ISC21-Descriptor-Track-1st" rel="nofollow noreferrer">https://github.com/lyakaap/ISC21-Descriptor-Track-1st</a></p>
  <p>in the first step it wants me to set this environment on my computer:
  I'm not familiar with yml environments and running to this error <a href="https://i.stack.imgur.com/2oJoT.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2oJoT.jpg" alt="enter image description here" /></a></p>
  <p>and I don't know how to solve the problem of ResolvePackageNotFound, should I install new packages? how to solve this?</p>