Of you want to run InDesign CC2014/2015 you need to update your OS to 10.10 or 10.11.
You're now four versions behind the current Apple system (El Capitan, 10.11). The further you fall behind, the more incompatibilities you'll encounter. You don't have to run the latest system software but it's a good practice to run recent software.
What are you actually trying to download? I think there are still a few older versions available that will run on 10.7 if your hardware won't support a newer OS.
InDesign CC2014/2015 works fine under mac os 10.9 but i don't know about mac os 10.10
Just want to let you know:
InDesign CS5.5 v7.5.3, CS6 v8.1.0, CC v9.3.0 and CC 2014.2 are running well on my Mac OSX 10.7.5.
The current version CC 2015 requires OSX 10.9. as a minimum.