Art upload requirements:
CMYK (for full color) and GREYSCALE (for black and white)
.tif file or PDF (not .jpg or .png)
Most phones, digital cameras will shoot at 72 dpi in RGB color mode. These will not be able to be printed since RGB is a projection mode (i.e., computer screen or phone screen) and 72 dpi is incredibly low-res for printing. You can adjust these settings and save as a .tif file in Photoshop.