I already own a CD install disc for Acrobat 6.0 standard. How do I use the serial no. to install on my current Windows 10 PRO PC with SSD?

As mentioned in the correct answer given above, Acrobat 6.0 is an extremely old version of Acrobat series. It has now been declared as discontinued product and its activation server is also not available. Even though you have installation CD, but it wont work as its activation server is disabled.

You can read this article for detailed information: End of support | Reader 9 and Acrobat 9 (and earlier) 

Thanks,

Akanchha