Activating my new Acrobat Pro licence

This is a user-to-user forum, for the most part. You should contact Adobe directly for help with this issue:
Chat support: https://helpx.adobe.com/contact.html?rghtup=autoOpen
(make sure pop-ups are not blocked; type "Agent" to chat with a real person)
Phone support: https://helpx.adobe.com/contact/phone.html
There's no email support.

Beware of people contacting you via the forums' messaging system pretending to work for Adobe! Only those with an "Adobe Employee" tag under their name are legit. Also, Adobe will never offer to contact you via Skype, or use an email account that's not under the adobe.com domain...

PS. You wrote: "what I’ve bought is full Acrobat Pro but without the support and upgrades available on the subscription model. Is that correct?"

Not quite. The "perpetual license" version does not have the same updates available to it as the subscription-based one. They are often lagging behind by quite a bit, if they are implemented at all for it. The rest is accurate, though.