In order to receive alerts your account needs to be verified. When you created the account you would have received an email asking you to verify your account.
If you have verified your email address and you're still not getting alerts, make sure you have alerts switched on in your account. You can find this under Account Settings and then 'Subscriptions'.
Scroll until you find 'Saved search alerts'
Here you can control if you want notifications and how you want to receive them.
Good to know: Saved search alert emails are sent every 24 hours rather than immediately when a matching advert goes live.