With Web Platform Installer riding off to the sunset, the old ways of installing Workflow Manager no longer apply.
I recently encountered this while trying to install Workflow Manager on SharePoint 2019 on-prem. As of the new year (2023), we no longer have access to the product installers in WebPI. More information on that can be found here: https://learn.microsoft.com/en-us/answers/questions/429383/web-platform-installer-end-of-support-and-sunsetti
After some research I found that Microsoft actually released a new package that simplifies the old process. They call it SharePoint Workflow Manager. It is what now powers the SharePoint 2013 Workflow platform and replaces Microsoft Workflow Manager 1.0 and Service Bus 1.1.
The installation was straightforward and only requires the prerequisite of downloading and installing Azure Service Fabric Runtime and then running a PowerShell command to create an Azure Service Fabric Cluster.