You can login by your PTC credentials and find the ThingWorx Analytics Extension on the below link:
Follow the blue marked circle in above screenshot. Do let me know in case of any question.
The ThingWorx Analytics Extension is located under the product ThingWorx Analytics. The screenshot you showed is for product ThingWorx Platform, this is why you do not see it there.
However from the record I can see, it seems you do not have a license for ThingWorx analytics, so you won't be able to see this product in the Software download page.
If you think you should have it or if you want to add it, I would recommend you contact PTC License Management, https://support.ptc.com/appserver/cs/lm/index.jsp