“This installer requires an internet connection” Fix: You need internet; Adobe servers still host Acrobat 2015 files.
Does it try to access the internet without user consent? Does it create registry keys unrelated to Adobe? acrobat2015webwwmuiexe
The "MUI" designation means it contains all supported language packs, allowing the software to automatically match your operating system's language or let you switch languages within the app. acrobat2015webwwmuiexe
You will be asked for a Serial Number (perpetual license) or to install in Trial Mode . acrobat2015webwwmuiexe
Based on the filename you provided ( acrobat2015webwwmuiexe ), this refers to the (specifically the "Continuous" track Web Wrapper).