I am guessing that the main issue is the documentation which does not make clear that dev and stable builds require a different instruction set – as said by @AnotherElk.
… maybe you are right …
Are you using Windows ? Might the second part, Windows, of the following post clarify this Windows / FP3 issue ? FP3: From 0.23 Android 9 to /e/OS 1.x - seeking clarity - #16 by aibd.