I bought these for my 6 year olds since all the parks are closed and they needed some monkey bar fun. Initially,I had planned to connect it between posts buried in the ground. I changed my mind once I got it,and I'm glad I did. You need to make this VERY tight to work properly and strong trees are necessary to do that (unless you're really burying posts deeply,probably with cement).
This took about an hour to put together and install. A helper is useful -- my kids were good for that. You will need a short ladder to get each side strapped around the trees.