It is important that you dont mix RGB and CMYK in your InDesign documents. Doing so might lead to very dark plots since the plotters color handling averages everything.
Also it is not good in general to work with mixed color spaces. It is recommended to only use CMYK for the plotter. At least when working with InDesign.
We have made an example plot that you can use as reference.
The poster contains info about what color space is used, and sample color values that you can use for your own reference.
You can find the physical version on the wall at the plotter itself, and download the PDF here: