I think you’re just missing one more level of reference to get the “next” url. The JSON response in the first screen shot has an attribute within ..._links.next, named href, so try expression {{ $resonse.body._links.next.href }} (or if you found that you needed to use the other syntax for the _links part, try {{ $resonse.body['_links'].next.href }}
If you have other issues getting pagination to work, it could help to have a working example to start with.