ENVI-met organises the output into different folders in order to keep the data structure more clear:

\..\atmosphere:     Main Data Atmosphere  (_AT_...)
\..\soil:           Main Data Soil (_SO_)
\..\surface:        Main Data Surface/Fluxes (_FX_)
\..\log:            Text Outputs from the Model (logs)
\..\receptors\..:   Data at the different receptors in the domain 
                    (one folder for each receptor) 
\..\inflow:         1D Profile at the inflow boundary
\..\BOTworld:       Data for the BOTworld model

If the output directory doesn't exist, ENVI-met will create it (if possible).
If this still not works, ENVI-met will write it to the \output sub folder of the models home directory.