The support for importing automatically the Yeo cortical parcellation was added to the FreeSurfer import function. If you have files named 'lh.yeo2011_7networks_n1000' or 'rh.yeo2011_7networks_n1000', they should be added automatically as an atlas labelled "Yeo 7 Networks".
Same for the 17 Networks.
https://github.com/brainstorm-tools/brainstorm3/blob/master/toolbox/io/import_label.m#L696-L699
Instructions to compute these files can be found here:
https://neuroimage.usc.edu/brainstorm/Tutorials/LabelFreeSurfer#Cortical_parcellations
However, I recommend you use the Schaefer atlas from CAT12 instead (the updated version :
https://neuroimage.usc.edu/brainstorm/Tutorials/SegCAT12#Cortical_parcellations