"He was not allowed to swim."
Translation:Han fick inte simma.
Good question, as a native speaker I hadn't thought about this construction before. And yes, I think it's a way to express the continuous aspect, often - but not always- with the added notion that the activity is ocurring somewhere else. So we say, "Hon är och handlar", "Han är och spelar badminton", "De är och hälsar på sin mamma".
It's a set expression. Basically 'lov' means 'permission', so fick inte lov att means the same as 'was not allowed to'. This expression isn't taught in the course.
All accepted answers can show up depending on what you input, since the system tries to match what you put to the closest accepted answer. This is one reason why we're sometimes reluctant to add answers that sound almost, but not quite, right.