The following might be worth a try, on the chance that it might apply in your case.

I tried several times this morning to download Ancestry DNA data file to my laptop in order to enter the file at Gedmatch. No luck the entire morning. I followed instructions to click on the Ancestry screen for download, provided my email address, went to my email and opened it and clicked on the download screen, which said to wait. I waited. Nothing happened. I tried this for several hours.

Finally--

Suspecting the contrariness of Internet matters, it occurred to me--what if I had to use the same browser for both operations? All this morning I had had Ancestry open in Google and I had had my email client open in Internet Explorer.

So I closed everything out and began again. Re-opened Ancestry, again in Google. But this time I also opened a second Google screen, this time for my email provider. Again received the Ancestry notice to go to my email, again I started the email, again received the Ancestry notification that I was to click on the download link, and again clicked on it. This time I was directed back to the Ancestry screen. And this time--it worked. After many tries earlier with Google in one screen and IE in the other.

Incidentally, I've found in the past that if I am trying to copy an Internet address, to enclose as a link in an email, that I have to click on and save that Internet address in the same browser as the one I have open for the email, otherwise it is impossible to click completely on the browser website address. Remembering that quirk in the system, or at least in my own computer, was what made it possible for me to figure out the DNA download quirk.

Hope the above works for others.