Notifications in GitHub come directly from repos so the first step is to check you have access to the repo you want to receive notifications from.
Step 1
Check your repo access
Sign in to GitHub
Navigate to your profile » Settings » Repositories
Step 2
To receive notifications from a repository you need to ‘watch’ it.
Open the repository and navigate to ‘Watch’, then select the category of notification you want to receive.
Step 3
After watching the repositories you’re interested in, you may want to configure your notifications further. Go back to your profile and navigate to the notifications menu.
You can choose whether to receive notifications to your preferred email address or to your GitHub notifications inbox.
If you’ve opted to receive notifications by email, you can then filter/forward them by using Outlook rules, e.g. to disseminate to a person or team who may not have a GitHub account.