I originally had the linkage usage set and thought this might be the problem, so I cleared the field. I did not realise that it would default to 0.
However the download still does not work for me.
Using Windows Edge, I get the left hand popup, an overlaid progress wheel and then back to the left popup. I have never seen the right hand popup in your figure (possibly because this is Firefox specific?).
I tried deleting all occurrences of my email from the subscribers list but this made no difference.
I tried a different computer and user account and the result was the same
I tried using Internet Explorer 11 and the download popup does not appear (the url is given as http://www.coastalsea.uk/#unlock)
I hope this gives you a bit more to go on.
