Copy address of project repository.

Open Fork application and go to File -> Clone. Paste your url in a new window and click Clone.

Open new generated folder in Visual Studio Code and paste next command to Terminal in order to authorize your hub org:
sfdx auth:web:login -d -a devhub
Authorize to your Salesforce org in a new opened login page:

Create a scratch org:
sfdx force:org:create -s -f config/project-scratch-def.json -a app
Push the app to your scratch org:
sfdx force:source:push
Open the scratch org:
sfdx force:org:open