Hi, I'm trying to set-up FB authentication and registration handler in a dev org. Steps pursued below and couple of questions.  Any guidance/feedback, much cherished;

Source of guidance -- steps followed in this trailhead. https://trailhead.salesforce.com/en/content/learn/modules/identity_external/identity_external_social,   

My objective is to enable Sign on via Facebook feature and Update the Apex Registration Handler. 

A couple of strange things are happening:

1) Following instructions in trailhead -- section titled 'create an Authentication Provider', after I create the facebook auth provider, steps for  a) copy the test-only initialization URL and paste into an (incognito) browser, b) log-in to facebook page (used my personal account), c) when prompted to authorize your app...the next image I see is an XML image -- 'does not appear to have any style association with it' 

2) To pass the challenge -- the Github link is taking me to an empty page (see attachment) the Google https://github.com/salesforceidentity/IdentityTrail-Module3

Question: 

#1 above, what are the requirements prior to setting up an Oauth? (i.e., I have a community setup, do I need to have My domain enabled? anything else)

#2 am I using the right link?

Thanks for your time, look forward to your feedback.