Translation:The strategy is simple, we must score more goals than them.
"than they" er også god engelsk. Se for eksempel https://www.quickanddirtytips.com/education/grammar/than-i-versus-than-me .
Here is another example of how we are being made to answer in incorrect English in order to move on. The correct response is "...than they" or "...than they do." This is why I keep quitting Danish. I get so frustrated by having to answer with poor English. I wouldn't expect a Dane to speak incorrect Danish to satisfy my stubbornness, so why should I be expected to "dumb down" my native English to satisfy you?