Windows blocked the installer. The download is fine.

Get past it in two steps

1. 01

   Choose More info

   The blue panel shows two buttons, and neither of them installs anything. More info is the small link above them.

2. 02

   Choose Run anyway

   The panel expands, names the file, and offers Run anyway. Notula installs and updates itself from then on without repeating any of this.

Why Windows says that

Nobody should click past a warning they have not had explained. SmartScreen checks a downloaded program against Microsoft's reputation service: who signed it, and how many people have run it without trouble. Notula's installer has no code-signing certificate yet, so there is nothing to look up, and the wording Microsoft chose for that case is unrecognised app.

It says nothing about the file itself. The same panel appears for every unsigned installer, including the first build of software you have used for years. The download comes from the releases page, built by a public workflow from the tag it names.

It goes away the day the installer has a certificate. That is a code signing account and a hardware token, not a technical obstacle, and it is listed openly on the status table. macOS already has its certificate: that build is signed and notarised, and opens with no step at all.

It still will not run

• There is no More info link

  Some builds of Windows put it under the panel rather than above the buttons, and a narrow window hides it behind the title. Widen the window, or press Alt to reveal it.

• The browser deleted the file before you ran it

  Chrome and Edge sometimes discard an unrecognised download on their own. Open the browser's downloads list and choose Keep, then run the installer from there.

• You are on a managed PC

  Some company devices block unsigned installers outright, and no click gets past that. There is nothing to work around here: it needs the signed build, and until then Notula will not install on that machine.