For example, this doesn't work

It needs -s , to work.
(spotdl -s https://open.spotify.com/track/08mG3Y1vljYA6bvDt4Wqkj?si=SxezdxmlTx-CaVoucHmrUA)
You might have installed spotDL using pip and that'd install v2. Please follow the exact procedure provided in Readme.md to install v3.
Yes I did, didn't know it they were for v3. Maybe the fact that they are specific to v3 should be added to the Readme.
An indication would be helpful to first time users
Also, on this step

It should be cd spotify-downloader instead of cd spotdl
Since that is the name of the folder that git clones.
Right?
How about you fork this repo, make the necessary changes and create a PR. Wouldn't that be great. And we'd also appreciate it.
I had to rollback the changes. Please see the PR you opened for more details.
Most helpful comment
Also, on this step

It should be
cd spotify-downloaderinstead ofcd spotdlSince that is the name of the folder that git clones.
Right?