This error means that port 80 is not open in the machine and an offline license should be requested.
1 - In the licensing dialog, click on Do Offline Activation and click OK:
2 - You will see the following screen, where you will need to click on Generate to get the offline activation code:
3 - You will see the following message to send us the offline code so we can activate it:
4 - Click on OK and copy the offline code and open a ticket with us.
5 - We will then activate the offline code and send you a new activated code so you can paste into the offline licensing dialog and import it.
6 - After clicking on import, erwin will launch.