My client sent the print PDF I provided him with to a print studio. They replied that the black CMYK profile is set to 100/100/100/100 and they need it in 64/55/53/100. How do I fix that? I'm designing in Photoshop and exporting with Bleeds in Illustrator.
What the printer is telling you is that you're over-inking your rich blacks. Maximum ink coverage is almost always much less than 300% total (275% in this case), depending on the press and the paper, so a rich (or "built") black can't be 100% on all plates. There's more information on black vs. rich black here.
I'm guessing, since even RGB black from Photoshop isn't 100/100/100/100, that you've accidentally used the Registration black somewhere in the document. Registration black is only for registration marks, never for live art or text in a document.
To see exactly where you have problems, if the above hasn't made it obvious, open the PDF in Acrobat and under
Tools > Print Production select
Overprint Preview and check the "Simulate Overprint" checkbox. As you move your cursor around the black parts of your artwork, watch the figure for "Total Area Coverage". Anywhere that number goes over 275% is a problem you should fix, either in Photoshop or Illustrator, depending on where it was created.