@leanne No problem. The unallocated space will actually be expanded on first boot of Retropie and brought into use. The image you download is compressed you see, so that there is not wasted empty space in it.

Update:

PI Imager on Windows 7 runs fine but stuck at the downloading progress. I managed to complete the task with UUByte DMG Editor.

Appreciated for all the suggestions in above! Have a good day!

we do not support third party images.

@pojr Cool, glad you got it! I meant to mention that one as well as I has tried it, but it didn't fix
the issue for me.

i would remove the pi from the case and run it caseless whilst you’re debugging. fans and cases are additional points of failure.

i would also ask these kind of general pi support questions on the raspberry pi forums as you’ll probably get better answers. you’re not at the retropie stage (and we don’t support pi4 officially yet)

You'll need to use something like pi-shrink to make the image be as large as its contents (vs. the full copy of the card).

https://github.com/Drewsif/PiShrink