I properly installed CLI. In a command window, I enter:

sfdx force:auth:web:login -d -a DevHub

in order to log in to the trial Dev Hub that I created. The aforementioned command opens the Salesforce login page in the web browser, so I log in using my Developer Hub Trial Org credentials and click Allow. After that, web browser show me an error: "This site can't be reached. localhost took too long to respond".

This is the URL that Salesforce use after I authenticate in the browser: http://localhost:1717/OauthRedirect?code=aPrxbOND3gL_2LbSR7rKPdvD0XBVk2YpErl3pphY2f3xvZ1wf5SSPJByDleRLPMtzCQWnNGAdg%3D%3D&state=f2f8254fac23

I don't know what happen.

Very frustrating. I've attempted this challenge in the DE I was previously working in where I created the reports that need to be added into the dashboard. I have now tried it in two separate NEW DEs where I recreated the reports and built the dashboard. The error code has changed from yesterday but the end result is the same:
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: HAKDYYXE
Any suggestions on how to move forward. The Dev Community account is new. However, this would be my 129th Trailhead badge.