First, you need to get the utilities out of SMRT into the right format. Within SMRT, go to Run Manager, select Export, and under "Save as Type" select "Generic Conjoint File (*.hbu)". Try uploading that utility file (*.hbu format).
SMRT converts the group-based utility information into pseudo individual-level utilities. If you are interested regarding the math for that, it is described in the SMRT manual, under the topic "How the simulator uses latent class data" (it's one of the Appendices in the SMRT manual).
Essentially, we create a weighted average of the utilities from the groups for each respondent, where the weights are the probabilities of membership that each respondent belongs in each group. So, if I am 60% likely to belong to group 1 and 40% likely to belong to group 2, then my individual-level utilities are given by taking .6 times the utilities from group 1 + .4 times the utilities for group 2.
Pseudo individual-level Latent Class utilities developed in this way are generally considered inferior to HB utilities as developed under the CBC/HB system.