Facing an issue with the Trail head challenge under User Authentication :- Set up My Domain for your Developer Edition

Multiple issues faced

1. I created a new domain  myorgpj-dev-ed.my.salesforce.com

    and even I was able to login into the above domain.

    (but there was no check box in the my domain config page to deploy to other users , 

     This is one stop which I couldnt complete as per the challenge instructions. I searched if anyone solved this issue but couldnt find any workaround or satisfactory answer)

    when I completed the challnege when 'checked the challenge to earn the points'

    I get the error message :

Challenge not yet complete in xxxxxxx ( my user id ) 

There was an issue processing your verification. Please refresh the page and try again.

So I am stuck here - unable to complete the challnege

2. After creating my new domain, I am launching the developer edition  , hoping I will be able to continue to the next challenge of SSO

   Trailhead launches the new org with the following message

  Want to connect this org for hands-on challenges?

  with the options No make me login, Yes Save it 

  In both cases I get the message '404, we couldnt find that page'

Did anyone face such issues ,  anyone able to help please.

Let me know if I anymore information is required to further understand my issue.

 thanks for any help.