Downloaded, installed and runs without issue on an external drive.
On the download page there is a link to request a license key. Once you do that, the confirmation page is in German but, basically, states they’ve received your request. The reply with the license came within seconds of requesting it. I can only suggest trying again for those of you who did not receive that email. Otherwise, perhaps you want to try contacting their support team through the email address listed on the contact page on their website. (I would paste it here but am unsure if that is allowed)
FYI, when inputting the key, it asks for name and company. Check your email with the key, in mine both those fields contained my email address so that is what I put in those fields when registering and it took without issue.
Thank you to O&O and SOS for this.