I am doing the Trailhead module Quick Start - Salesforce DX and am on step 3 'Create and Test Our Scratch Org'.
But, have the error message 'We could not find a scratch org whose organization name is 'Dreamhouse' belonging to this Dev Hub. Make sure to create a scratch org with a definition file that sets the 'orgName' property to 'Dreamhouse'.
My Dev org playground is;
aimit.crm.academy@playful-badger-em3zf0.com
And, scratch org;
00D5E0000009bvQUAQ, username: test-16go88iapr2r@example.com

I can see the Dreamhouse App info all pulled in from Github repo  but am not sure why Trailhead can't see it. I have repeated this task twice in 2 different Playgrounds and then deleted them. No success.  Please can anyone advise?