I’m not sitting in front of my system, so I’m doing this from memory…
Don’t just navigate to AddOns on the lefthand side of the screen, but also click on the title AddOns to select it. Then at the very top left of the AddOns screen is an icon that looks like an opened package. Click on this and then select My AddOns. Navigate down to something like Video Inputstream and select, and then enable inputstream.adaptive. Doing that will allow you to download and install iPlayer WWW.
THEN under the iPlayer WWW settings, make sure you change it from DASH to HLS. There are some working DASH streams, but they’re wonky, and if there isn’t a DASH stream available, it tends to crash iPlayer. The HLS streams are still around, so I’d just use these until they go away.