The AUR PKGBUILD shows a pretty simple recipe:

build() {
  arch-meson "${pkgname}-${pkgver//+/-}" build
  meson compile -C build
}

package() {
  meson install -C build --destdir "${pkgdir}"
  # permission fix
  chmod 755 "${pkgdir}/usr/bin/ascii-draw"
}

I’ve been seeing arch-meson often used, but haven’t explored what it does. Some day…

Though it’s way more fun to use text specification, like the one referenced by @fratermus@lemmy.sdf.org

I don’t have an answer for you, I’d never heard of ASCIIFlow, but holy shit that takes me back to an oooold piece of DOS software called FormTool. Used to make dungeon maps and character sheets and such with it back in the early 90s. Good times.

You might be interested in Emacs, it has (among many other things) artist-mode where you can draw with your cursor and obtain good ASCII art

I’m not sure why you wouldn’t want the ASCII-Draw flatpak, but that’s not the only way to get it:

• there’s a Snap
• it can be installed from source
• there’s also an AUR package

But maybe you’re not on Arch, don’t like Snaps (can’t blame anyone for that) and don’t want to install from source (same)? What type of package are you looking for? Only native package? For which distro?