Once you have been assigned a license, you can register the IDE using an offline activation code.
To generate the activation code, login to your JetBrains Account and click the Download activation code for offline usage link.
Next, run the IDE and open the License Activation dialogue box by clicking Enter Key if you are prompted to do so at startup, or from the Help -> Register menu inside the IDE.
From the License Activation dialogue box, select the Activation Code option and copy/paste or drag and drop the entire text file of the activation code into the empty field, then click Activate.
You can double-check to ensure you are properly registered from the Help -> Register or About menu inside the IDE. It will show who the installation is licensed to, as well as the subscription expiration date.