INSTALL of UNITY 5 fail- 'write permission error'

Unable to open UNITY 5 on install? on MACOS 10.9.5. If you have an answer that invoves TERMINAL can you give step by step instructions? I’m a beginner user of TERMINAL (& UNITY)

Failed to write “/Library/Application Support/Unity/Unity_v5.x.ulf”. Please verify you have write permissions to this file.

As the error says, do you have access to the /Library/Application Support/Unity/ folder? It’s possible if you are a regular user and not an admin that this location is unavailable to you, in which case talk to an admin about how you can get access.