Hello & welcome aramok !
for your A590 there's NO CHDK available at the moment,
perhaps there may be a test version in some months...
You can NOT use a CHDK version for an other camera, the CHDK MUST fit to the camera model AND the original Canon firmware on it, so the CHDK for the A570 is definitively not working on the A590.
You will see it in the NEWS on the
CHDK Wikia Homepage when a version for your A590 ist available.
(You can also follow the A590 development in this thread: A590.)