Here is the steps on how to download and Install OBIEE 12c client tool installaton.
Go to Oracle Business Intelligence Developer Client Tool (126.96.36.199.0) section and download the client tool.
once Downloaded, Copy into a new folder and unarchive/unzip the zip file.
Double click on the 'setup_bi_client-188.8.131.52.0-win64' file and the installation window will open
Oracle Universal Installer Window will open. Just Click 'Next'