The thing is, for an autotransformer, the autotransformer rating is = (load power x [series winding voltage]/[series winding voltage + common winding voltage].This link to Acmes catalogue discusses the kVA relation in detail:
The 1.5 kVA rating is only accurate when connected as an insulation transformer. When installed as an autotransformer the kVA rating is 5-10 X greater and the 1.5 has no relation to the autotransformer any longer, only for naming purposes as Acme brings out.
Others call that the "apparent rating", knowing a portion of the power delivered to the load is "conducted" while the remaining power is transferred "magnetically".
In this case the factor will be (32)/(208+32) = 0.1333 or you divide the load power by 7.5 to get the rating of the autotransformer!