Can't say I've used the product, but just looking at what comes as part of that jacket... there are multiple color choices. One of them already HAS white pocket stripe and solid white lettering. Use that as your base and don't change those parts colors. It looks more like you are trying to start your coloring from the teal version of the jacket.
The jacket includes three stock texture variants. Please, note, I don't know if what I'm gonna remark now happens for everyone that has this product installed or if it's actually an issue only on my end. The thing is that the 3rd texture, which is the one I used as the base where I modified the colors for the DIK jacket, has the wrong preview. I mean, it supposedly should look navy with dark orange sleeves and other minor details in that color. As you can see in this screenshot.
However, when I apply that Jacket 03 texture to the base jacket (which uses the Jacket 01 texture by default), what actually happens is what you can see next.
It goes from this:
Jacket 01 texture (default)
To this:
Jacket 03 texture (the base for the DIKs)
Everything that is left to do to get the final color combination for the DIKs is just modifying the base color channel of the different surfaces of the jacket wherever is necessary.
A tip: if you use the surface selection tool (Alt + Shift + M), hovering over the jacket with your mouse cursor will help you distinguish better the different surfaces (I think they call these material zones at Daz) that compose the jacket. Simply click on one and it will get selected for you to edit its values under the Surfaces pane.
Personally, I used this pic from the game as the reference to get the colors right.
, hence the capital BR on the jacket. If our dear doctor hadn't bothered to adapt these initials for his VN, Fuckface and the rest of the characters from Being a DIK would study in Blue Rabbit instead of Burgmeister & Royce. Good call, doc. Good call.