Some organisations require applications to request access before allowing access to any data (including notifications) about their repositories.
To check if Gitify is approved by your organisation you can go to settings, then click on Gitify and scroll to Organization access.

If you want to use OAuth to authenticate with Gitify, first create a new application within GitHub → Settings → Developer settings → OAuth Apps.
Complete all the fields, ensuring you use https://www.gitify.io/callback as the Authorization callback URL. Once saved, click on Generate a new client secret to get a client/secret pair that you can use with Gitify

You can debug Gitify by pressing alt + command + I. This will open the dev tools and then you can see any logs, network requests etc.

You can contribute to Gitify by opening a pull request @ gitify-app/gitify