The way I understand colors in Ignition is that they’re a complex data type. You can represent them in a few ways; the simplest is by a string name like ‘red’ or ‘blue’, and the most common is as a ‘tuple’.
color(75,255,71) is a nice light green, for example.
Are you looking for a continuously variable tint number, or just to color something red or green ?
The easiest way to change the color of a geometric object is to bind the StrokePaint or the FillPaint to an ordinary Tag, and use the color/value table.
Also: remember that an INT is an 8-byte datatype. While memory is plentiful, you probably don’t need a 64-bit value to express a color.
EDIT: I watched the video you linked to and it shows the color/value table that is available when you bind a Color to a Tag or Expression. I followed the same steps, using an INT DB tag, and didn’t get the same error message as you did.