Q: Apple Music purchase song vs membership

I was trying to download a song, but Apple Music Membership came up, if I said "Not Now" it cancelled out and I couldn't just buy the song. I like just buying a song when I want it. I did the trial for Apple Music, but now I realize that I can't use the song that I downloaded to add to a video of picture compliation that I'm making for personal use.

1) Is it possible to still just buy whatever song I want without joining a membership?

2) Is it possible to use a downloaded song in Windows Movie Maker picture video?

I was using my iphone 7 plus for the download. I was using an HP computer with Windows Movie Maker to make the video.

Thank you!