I think I followed all steps which I have found so far but the download link for my alpha test isn\'t working.
I uploaded the app 3 days ago, created a google group
Sign in to your Goole Play Console.
Select your app.
On the left menu, Select Release management -> App releases.
Select Manage Alpha or Manage Beta.
Manage testers, click on right side down arrow.(Just below CREATE RELEASE)
Choose a testing method: select Closed Beta Testing.
Next Create list or select the name of your list.
Feedback Channel: Enter your email to get feedback from testers.
Copy Opt-in URL and send it to your testers.
Now once you completed, Google Play servers takes time for any publishing builds alpha or beta. For me it takes 15-20 minutes to available.
Sometime clear cache of your browser and refresh link. will work.
Once link is available, Open it in your testing device and click on below link
Download the *APP NAME* app on Google Play
Press the Update Button. After installation you can test it.