I have been on that page, but if I read the instructions for installing DM 4.8, I stumbled upon this:
You must install Deployment Manager if you are using it on-premises. Because Pega Cloud Services manages the orchestration server in any Pega Cloud subscription, Pega Cloud Services manages the installation and upgrades of Deployment Manager orchestration servers.
To install Deployment Manager on-premises, do the following steps:
Install Pega Platform 8.1, 8.2, 8.3, or 8.4 on all systems in the pipeline.
I don't see Pega 8.5 mentioned.
That's the reason I am a bit confused.