Downloading the executable file can be difficult. You can download the executable file from this link.
Here is a step by step process of installing Cassandra BD.
Step 1: Download the setup from here
Step 2: Start the installation.
Click on the I agree and click on next.
Select the source folder and click on Next.
Click on Automatically start Data Stax DDC Service. Click on Next.
Click on Install.
Uncheck the Register and click on Finish.
Step 3: Open DataStax
Now you can work with the Database.
Hope it helps.