TIME SENSITIVE deadline is tonight pls help!

Time sensitive if anyone can help- I made an ad, when I export as a JPG it’s nice and deep black, but when i export it as a PDF it comes out very faded - on my computer screen it looks fine but on an iphone it looks faded. I tried adding diff adjustment layers to fix it up but nothing is working - any advice?
won’t let me upload a pdf but I took a screenshot of what it looks like as as pdf on a phone
2 files


What color mode are you using? CMYK or RGB?

I’m using CMYK…

That’s why, when you save cmyk pdf’s look faded.

find a picture of black and put that in instead as background