Downloading older versions

I’m trying to download an older version of sketchup to use on my computer. Most grateful if anyone could tell me how to do this. I;ve tried everything thing on this page.
https://help.sketchup.com/en/downloading-older-versions

Thanks

Your profile suggests you’re looking for SketchUp 2015, but I believe you have a license for SketchUp 2016. You will find that there are posts to archived installer in the forum. Look at this as an example:

In the first post there you can click the black triangle to see the links to SketchUp Make 2016. Assuming that you don’t mind having 2016 instead of 2015, take whichever one you need (64 bit or 32 bit), and install it. In the welcome screen click on the License tab, and Add License, to put in your serial number and authorization code.

There is a small complication, in that you may have bought via Elmtec, and you would normally contact them to get your license information. It’s the weekend, and looking up the license for someone who hasn’t been under support for over four years, might not be their first choice of things to do today!

In your normal email address, can you say what comes after the @ character? If it matches what I see on the license, I can send the numbers you will need.