The cookies contain things like `frequency=7; transmissions=kxkxkxkxshMy59kxkxkxkxsh`

Do a bunch of requests and order the transmissions by their accompanied frequency.
Remove the constant garbage around the changing letters and get some Starset tracks to form the flag

pctf{Down_With_the_Fallen,Carnivore,Telescope,It_Has_Begun,My_Demons}