Why this search has such a strange results page
A very large number of people want a free, simple, friendly way into music production and know exactly one product by name. When that product does not exist on their operating system, the search does not stop - it gets served by sites that monetise the gap. The result is a first page dominated by downloads that are not what they claim to be. The useful answer is boring and short: it does not exist, and here are three real things depending on what you meant.
GarageBand is genuinely good, which is the whole problem
It is not popular by accident. Free with the hardware, a well-chosen loop library, a gentle learning curve and a clean upgrade path into Logic Pro - it is one of the best pieces of free software Apple makes. That is exactly why the Windows version is missed, and why the honest response is to identify which of its qualities you actually need rather than to hunt for a clone.
The browser answer, and its limits
A browser studio solves the operating system problem completely: Windows, ChromeOS, Linux, a school laptop with no admin rights - it does not matter, because nothing is installed. GOONS runs 20+ instruments that way for €9.90 a month with seven days free. What it does not do is work offline or host plugins, and if either of those is a requirement then a desktop DAW is the right answer and Cakewalk or Waveform Free will cost you nothing. The wider comparison is on the alternatives hub, and the machine-constraint case on make music anywhere.