Why can't i find the mission?

I just got a new mission in Fortnite "Cleared!" and there I should use a medbot in a rescue the survivors strength level 23 but in plankertoon I see but no rescue the survivors strength level 23

You have to look where the medbots are e.g. Downtown or something

Are they hidden?

Yes, you can say if you start a mission. First, explore the whole map

Ok thank you then I'll have a look

Thank you very much