Here to help. I am not sure why you have a screen shot of a vertical profile, which suggests to me you opened the spectral library as an image. To examine the spectral library data you need to open the file as a spectral library, not as an image. Did you open it as a spectral library, and could you display spectra? If you did this and can display spectra, resampled to M3 bandpasses, you should be able to overlay spectra from an M3 cube pixel with the lab spectra. Let me know what you did and I can help more if the instructions above are not enough. Worst case is for me to try what you wanted to do with the exact data sets you used.
Ray Arvidson