In our product description for every artwork, we mention the following:
IMPORTANT: Please do not change the RGB color space of our templates to CYMK when submitting your artwork. Our templates are intentionally designed in the RGB color space to best match most customer's screen expectations. We will not reprint artwork whose template is changed to CYMK color space.
As stated, we intentionally have our artwork in the RGB color space because most of our customers have no knowledge of CYMK. Many of them submit files downloaded from the internet, which are RGB color space, and expect it to look accurate. If we print their artwork in CYMK, it does not work.
To avoid the hassle of switching color spaces, we encourage you to use our Photoshop templates without adjustments to the color space in those templates. Doing so will affect your artwork's output, and we will not reprint it at our expense.