After installing Oracle Clusterware, as described in Oracle Grid Infrastructure Installation Guide for your platform, you can install Oracle RAC Database software.

• About Image-Based Oracle Database Installation
  Starting with Oracle Database 18c, installation and configuration of Oracle Database software is simplified with image-based installation.
• Setup Wizard Installation Options for Creating Images
  Before you start the setup wizards for your Oracle Database or Oracle Grid Infrastructure installation, decide if you want to use any of the available image-creation options.
• Downloading the Software from Oracle Software Delivery Cloud Portal
  You can download the software from Oracle Software Delivery Cloud.
• Deciding Between Multitenant Container Databases and Non-CDBs in Oracle RAC
  Review the information to decide how to deploy your Oracle Database using the CDB or Non-CDB options.
• Installing Oracle RAC and Oracle RAC One Node Databases
  Understand the process to install Oracle Real Application Clusters (Oracle RAC) and Oracle RAC One Node Databases.
• About Deploying Oracle Databases Using Oracle Fleet Patching and Provisioning
  Oracle Fleet Patching and Provisioning (Oracle FPP) provides a standardized approach for provisioning, patching and upgrading software homes on any number of nodes from a single cluster.