If I understand you correctly, are you trying to select the your git repo for the
Download GitHub Release task.
How to use your own data?
You can try setting your own data to the environment variable and refer to it in your pipeline tasks.
1,To set a variable in scripts, you can refer to below example
- powershell: echo "##vso[task.setvariable variable=repoName]variableValue"
2,To set variables in the Pipeline edit UI page, you can click the Variables on the top right corner to add a variable.

3, Use varibles
in yaml pipeline
variables:
repoName: variableValue
configuration: debug
platform: x64
Then you can refer to these variables in Download GitHub Release task like below example.
- task: DownloadGitHubRelease@0
inputs:
connection: 'mygithubconnection'
userRepository: '$(repoName)'
defaultVersionType: 'latest'
downloadPath: '$(System.ArtifactsDirectory)'
Please describe your question in details, if above doesnot answer your question.