poly branches could indicate the numer of fingers in a device( never heard it described as such) , eg, width =1x 10um or 2x 5um. No of groups not a common name for multiplier.
Grouping is normmally associated with grouping common transitors or groups of resistors or both etc.
Are you using GAAFET process?
If yes, are you free to choose number of sheets per transistor? If yes, then this parameter might be an equivalent to fingers.
Of course above are only my speculations (I also don't remember to met such terminology).
In principium, all answers you should get from foundry (maybe they provides some tutorials).