Microsoft Secure Score (Office 365) link to try preview version does not work

I Suspect that the preview is being rolled out to tenants in the background and that you will eventually be able to access it.

Currently I have multiple demo tenants and at least 1 production tenant which can access the preview features. However I also have another production tenant which cannot (exact same symptoms as you) The only thing of note about this tenant is that it appears be one that historically has been towards the end of the queue when it comes to having tenant level features deployed by MS.