The email subscription form at https://fontforge.github.io/en-US/downloads/gnulinux/ gives a warning message that looks like this:

If I click on "Cancel", I can download FontForge (which, ignoring the fact that it's questionable to force people to disclose their email address, is the opposite of the form's purpose?)
If I click on "Continue", nothing happens, I don't see the download link, and according to errors messages in the developer tools, I probably don't subscribe to the newsletter either:

I'm using Firefox 60 on Ubuntu 17.10. In Chromium 66, the download link appears but I don't think that I'm subscribing to any newsletter either:

Expected behaviour:
Thanks for your work on FontForge :)
This appears to be a bug in Firefox. A breakpoint on submitting emails_sform2 triggers before the dialog box, but a breakpoint placed immediately afterwards does not, suggesting that Firefox stops executing code after escaping to the dialog box. That said, I don't think that Firefox will fix a bug for little FontForge, so I'll try to think of a work-around.
I can't download anything using Firefox. I'm sure if it's an actual bug in Firefox, they will try to fix it. My gut tells me that it's more likely to be a bug in the web site.
I can download only if I hit 'cancel' (on Firefox). Then the link shows up, otherwise it doesn't.
Anyway, I agree with belluzj that the whole setup with asking for e-mail before downloading is not a good idea. Just let people download without making them jump through hoops first, please.
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I can't download anything using Firefox. I'm sure if it's an actual bug in Firefox, they will try to fix it. My gut tells me that it's more likely to be a bug in the web site.