Try a Manual Offline Activation.
Save the code .txt file on your PC, then go here: https://www.captainsim.com/activ/offline.php (this link is provided on the installer as well, but AFAIK you can't click on it so you have to write it down) to manually activate it and you will be provided with a key .txt file (also to save on your PC).
Re-run the installer and use the key.txt file to unlock the installer and install the products.