Conversion Woes...

I spent most of the day fixing images I created in Adobe Fresco, on my iPad, then converted to printable formats on my computer. First were these 6 drawings of mine. My brother is going to get them printed and framed. I think they were in RGB format on the iPad then became dull when I converted them to CMYK on the laptop. It took me hours to figure out the best way to select the individual colors within the images, based on how I drew it, and finding approximate color matches. The next problem was when I exported a PDF from Illustrator that I originally drew in Fresco. In the PDF I there were thin lines around every brush stroke that wasn't showing up anywhere else before. My buddy Adam needed the artwork I made for his band's album, "Elysian," minus a the background, to put it on merch. He requested a PDF and I thought it was going to be as simple as one-click. Now I'm reading a 31 page guide trying to understand transparencies because I think that's what's causing the issue. I sent Adam some hi-res JPGs, hoping that they'll work for him, until I figure out how to fix this. I thought computers were supposed to make things easier for us.