For Windows - Download Unity 2017.2.4 - Here
For Mac - Download Unity 2017.2.4 - Here
For Linux - please use 2017.2.1 from this forum thread.
When Unity has finished downloading, click Run to start the installation.
1. When the Unity Installer window opens, click Next
2. After that, accept the terms and conditions and click Next
3. You will then see a screen called Choose Components. You will need to choose the following components from the list:
All other components are optional (but can be installed if you want):
4. After selecting these, click Next and choose your installation location.
This will start the download and installation process. Once finished, Unity will be installed.