Yes. A valid TV licence is required to watch or download any programmes on BBC iPlayer, as well as watching or recording live TV on any channel. Doing so without a TV licence is a criminal offence and you could be prosecuted and fined up to £1000 (or £2000 in Guernsey).
If you are 75 or over, visit the TV Licensing website to find out more about your TV licence requirements from 1st August 2020.
BBC iPlayer support can only offer support with using BBC iPlayer. If you have questions about the TV licence (i.e. if you think you may be exempt or you aren't sure about licence requirements) visit the TV Licensing website.