Legally, Adobe does not offer a truly "free" full version of InDesign CS6. It was originally sold as a one-time purchase.
Adobe no longer sells CS6. They discontinued it in 2017. You cannot legally download a free, full version of InDesign CS6 from Adobe or any authorized reseller because it was never freeware. download indesign cs6 free
To understand why people want to download InDesign CS6 for free, you have to understand the software's value. Legally, Adobe does not offer a truly "free"