Make sure you're following the artists you want notifications about. Audiomack sends you notifications the second their music drops.
To edit your notification settings:
On web: login to Audiomack.com and go here: https://audiomack.com/edit/profile/notifications
On the app: go to My Library > Click on your profile pic with the settings icon >
From your settings menu, select notifications
Another thing you can do is on your mobile device go to settings > notifications > and make sure your Audiomack app settings are allowed on your mobile device.