Download, why yes, you can download older versions of Lightroom. But that doesn't do you any good unless you have purchased license at some time in the past and have a serial number. Adobe doesn't sell licenses for older versions of Lightroom any more, and so you can't get a serial number for those any more.
If you want to purchase Lightroom Classic at this time, the only option is a subscription.
I'm not sure what you mean by "standalone". Lightroom Classic runs on your local computer, it does not run in the "cloud".