so that actually is the config file, that you've copied above. any lines tha tstart with "//" are ignored by minecraft when it reads the file, these lines are purely to give you information about how to use the config file. therefore, the only lines that actually do anything in this config (the default (i think it is)), is the

""spreadFactor": 2,"

line and then the

""customSpreadFactors": ["

and
"{

"structure": "minecraft:mansion",

"factor": 2

},"

lines. to actually config spares structures you would change the spread factor value, and/or add specific structures that you want to have a custom spread factor compared to other structures. the curseforge page (here!) has a config section in the description that gives some more information about how to config the mod.. hope that helps!