Using triggers, you can look up the player attribute for their Race. You can then pass that through multiple selection (bunch of if statmenets) and then adjust the game acordingly.
If you are using a trigger based spawner, (I imagine you are), you simply use a variable for the spawn type and set that depending on the outcome of the multiple selection.
If you are using an data based spawn system (yes, it is possible to make a footman frenzy map with no custom triggering at all), you use a validator to check player race. You give the main building all spawners (for all races) but let the validators enable only the one for the player's race. The same can be applied to upgrade paths and everything.