I am getting the following error when Refreshing Sales Data through Trailhead Data Manager:
"An error occured in your last data refresh.
Insert failed. First exception on row 78; first error: INVALID_CROSS_REFERENCE_KEY, Owner ID: owner cannot be blank: [OwnerId]"

I was following the steps in trailhead: https://trailhead.salesforce.com/trails/wave_analytics_apps/modules/wave_apps_basics/units/wave_apps_creating_wave_apps

So ive signed up for the dev edition org. Ive tried using my playgrounds. What am i missing? No matter what i do I keep getting the error "Challenge Not yet complete... here's what's wrong: 
The 'Trailhead_Data_Manager' app was not found. Please follow the requirements and ensure the wave enabled org is setup correctly." Where do i get this app? I assumed it came already installed when you signed up for the dev org. Can anyone please help, this is the last module i need to complete the trail. Thanks in advance.