I was trying to install Sims on an older computer of mine that is still running Windows XP (and will continue to do so), I got the legacy origin download and everything but every time I try to install it I get an 'your update could not be compleded. Please download and install the latest version of Origin from' and then it gives a link but I can't use that link or the version there because it's not compatible with Windows XP anymore. Is the legacy origin for XP just not a thing anymore?
You will have to 'downgrade' the new client when on Windows XP. I've explained for you how you can do that:
What is your exact problem?