The 64-bit version of PicoLisp is written in a generic assembler which is then built for target CPUs like x86-64, arm64, ppc64 or "emu". In "emu" the target "CPU" is plain-C, and this is used if the Android device is physically only 32 bit.

I'm confused too, how do you install the zip file?

Even one of the feedback posts mentions problem solved by "just installing the emulator version".

So I download arm32.zip in, say, firefox, and then what? Open it with PilBox just crashes. Clicking it in a file manager shows me the zip contents. Am I supposed to extract it somewhere? I'm not rooted so can't see the app dirs.

The easiest way seems to be to download it with a browser, and then immediately click on "open" in the little dialog which pops up in the browser after it downloaded the zip. It is then passed to PilBox.

Clicking on a Zip in the Downloads app works on some devices, but other systems only offer to extract the files which does not help here.

(1)download the zip (2)go to the downloads folder (3)tap/click the file (4) choose to open with pilbox

I'm assuming the 32-bit version emulates a 64-bit ARM CPU. Most Android devices are 32-bit, but a lot of the newer ones are 64-bit.