iMovie can’t be installed on “Macintosh HD” because macOS version 10.14.6 or later is required

I had my IMovie app in my Mac forever, being updated. But this last time I couldn't make it work. I work on it very well, but it was impossible to share the video.

After investigating, I realized that it is too old . I am trying to install the new version but iMovie can’t be installed on “Macintosh HD” because macOS version 10.14.6 or later is required. I have macOS version 10.12.6. I know it is old, but my budget is not allowing me to buy another one. Is there any way to find an older version of IMovie app to install in my computer?

Is there another solution?