[windows] How to run ssh-add on windows?

If you are not using GitBash - you need to start your ssh-agent using this command

start-ssh-agent.cmd

This is brutally buried in the comments and hard to find. This should be accepted answer.

If your ssh agent is not set up, you can open PowerShell as admin and set it to manual mode

Get-Service -Name ssh-agent | Set-Service -StartupType Manual