Hello. I'm trying to start on the Build A Data Model for a Recruiting App Project. https://trailhead.salesforce.com/projects/build-a-data-model-for-a-recruiting-app/steps/create-a-custom-object-for-reviews It asks that I install an unmanaged package but when i click on the link provided it says the app cannot be installed because the package is not found. 
"The requested package doesn't yet exist or has been deleted. If this is a recently created package version, please try again in a few minutes or contact the package publisher."
I need to understand roll-up fields (starting from the basics) so i need to complete this or is there another, newer module that will explain it better?

I'm doing the simple lightning components challenge and have hit this problem in my existing trailhead org and a brand new dev org that I've just created:

Challenge not yet complete... here's what's wrong: 
There was an unexpected error while verifying this challenge. Usually this is due to some pre-existing configuration or code in the challenge Org. We recommend using a new Developer Edition (DE) to check this challenge. If you're using a new DE and seeing this error, please post to the developer forums and reference error id: QVWBQHAG