Most of that code is irrelevant to your question. You're asking how to make a JLabel's colour shade from white to red depending on some parameter. White meaning zero, I suppose, and red meaning the maximum value. That's all. All of the JTable background is unhelpful.
So do you have a question about how to find the maximum value? Or just how to choose a colour value which is 0.693 of the way between white and red? Or some other question as well?
You are using a JLabel, you know. DefaultTableCellRenderer extends JLabel. But in any case the answer to that is easy: you call the setBackground(Color) method. Make sure there is a background colour to set by also calling setOpaque(true).