##update##
i got it working using pin 24 and a 3.3v pin. [see pi5 pinouts]
i have uploaded the install and script instructions so it works.
mine is set to 10 mins then shutdown
i have openautopro on a pi at the mo with a relay from https://timers.shop/ i use this relay with a script set on the pi desktop using gpio pins
to control the shutdown. i will post all the attachments i have and the instructions for you.
i have just purchased hudiy and a new pi5 so havent tested it out yet.
make sure to check pgio pins before connectiong anything up. the pic is for pi3b.