Just sign into your PSN account on your PS4 and follow the onscreen instructions.
If you’re activating a second PS4 or you’re signing into PSN on a friend’s system, you might want to learn a little more about activation to keep your PSN account secure but accessible, so you can safely share selected account benefits.
You can also activate a system as your Primary PS4 later. Go to [Settings] > [PlayStation Network/Account Management] > [Activate as Your Primary PlayStation 4] > [Activate] and follow the instructions to do this.
Only activate your own PS4 as your primary system. This is to make sure that everyone who uses your home PS4 can keep access to all shared features and services, even if you’re signed into PSN elsewhere.
To avoid accidentally activating your friend’s system on your account follow these steps:
What is activation?
Activation authorises a device to access your PlayStation Store content, subscriptions and other account features. You can activate one PS4 as your primary system and activating another will switch your primary system.
Only your own PS4 should be activated as your primary console.
Here are some of the PSN account features that you can only use on your primary system, so you can’t use them on a temporarily activated PS4:
Here are some of the PSN account features that other users can share on your primary system, so they’ll lose access if another system is activated as your primary PS4:
Why can't I activate my device?
There are a few reasons that device activation may fail.