Low albumin can suggest many different illnesses and/or conditions, the most likely being pancreatitis (often the result of a high fat
diet), internal parasites, poor quality
low protein diets, severe liver
disease, mange, internal blood loss, excessive IV fluid therapy ... and also chronic kidney failure.
So the difficulty is getting an accurate - and confirmed - diagnosis.
Assuming it IS CKD, then it is at a very early stage and a restricted low-protein diet is certainly not necessary.