Condensing is taking two (or more) independent Player staves and merging them together in the score (while maintaining separate staves for parts and other layouts). So if you wanted to do this with Condensing, you would create four separate Players: SATB – and then condense them together in the Score Layout.
Arguably, for vocal writing (where you are hopefully not producing separate parts for each voice), there is little need to use Condensing. You could simply use one Soprano Player, labelled “Soprano / Alto”, and one Bass Player, labelled Tenor / Bass.
There is also Dorico’s Divisi feature, which splits one Player’s staff into two or more staves, each of which can have its own label. This may be of more use if the staff list changes in the piece.