In general, you can upload files in either color space. If possible, we recommend that you create your files in the sRGB color space or convert them if necessary, and use these for uploading to our shop.
Why prefer sRGB? We use many 12-color printers in our production, which have a wider color gamut than a standard 4-color CMYK printer. By keeping the color profile in sRGB, you retain as much color information as possible and have a broader color range. This allows us to achieve the most vibrant colors.
If you have any questions on this topic, please contact our customer service team.