If you want to create a Flow you don't have to start in a particular document library. You can click the Office waffle menu to go to your flows and create the flow there.
Depending on what you want the Flow to do, you will need the respective permissions, of course.
Edit: Your screenshot shows the command tools of Classic experience. You will only see the Flow command in the Modern experience. It looks like this:
Also, the Flow command will only be visible if you have at least Edit permissions to the library.
But you can go to your Flows page via the Office App launcher at the top left. It looks like this:
If you don't see Flow in the App Launcher, even if you click All Apps, your license does not include it. You may want to talk to your IT department if you need a license that includes Flow.