adobe lightroom6 download

Hello,
I’m currently trying to download Adobe Lightroom 6 to my computer.

However, Adobe says this product is no longer available to use it. At the time of the purchase, I received the order confirmation which includes a serial number of Lightroom 6 through email instead of CD. But now, I cannot find any information about Lightroom 6 on 'order history' at the website. Adobe website confirmed that Adobe Lightroom 6 is successfully registered, but I am unable to use it. The customer service told me to contact the Adobe Forum because they already stop supporting the previous version. Is there any way that I can download Adobe Lightroom 6? Please confirm about this problem and reply as soon as possible. Thank you.