Yes. You can add as many Arlo devices as your subscription plan supports. If you already have as many devices as your subscription plan supports, you must either upgrade your subscription plan or deactivate one of your existing devices before you can add another Arlo device to your account.
To add a new Arlo device to your existing Arlo account:
For more information about subscription plans, visit What are the available Arlo subscription plans and how much cloud recording is available?.
For more information about deactivating an Arlo camera, visit How do I deactivate a camera from my Arlo account?.