Interesting - thanks for the prompt response. Sadly still no green download link for me.
But your reply inspired me to try it from my own network and behold, there it works!
I suspect that my clients Internet firewall/proxy security is blocking some part of the page e.g. I see that it contains a hardcoded link to some javascript at http:/10.250.242.55/piwiki/... that IP address doesn't seem to resolv to a name for me, on either network.
So that might well be regarded as suspicious. By me at least.
Cheers,
Robb.
P.S. I also wonder why that captcha step is even necessary, when I can download the crown jewels (ONTAP) without having to jump through that hoop.