See above question.
The installer file is always downloaded to the folder you choose to downloading when you use the "Save as..." option. Please go to https://todoist.com/windows, right-click on the download link, choose "Save as" and select the location you want to download it, then launch the installer from there.
Now I can't sign in. I get notes like this one to my email address, but when I type it into the sign in page is says something like user not found.
David, I didn't think that as things got tough, you would disappear. I do need help.
I now see "Unknown" as your username. Did you delete your Todoist account? In that case, I can't really assist you with the login issues as I need the email address of your Todoist account. Please respond using your new Todoist account.