Just installed, doesnt work at all

yeh i get the same thing.

1+ We need the developer to respond on this issue.
The plugin has not been updated for a long time either.

You should just set the stream name in the shortcode.
For example:
[embedTwitch username="TWITCH_USER_NAME_HERE"]

Didn’t work for me either… I did [embedTwitch username=”TWITCH_USER_NAME_HERE”]

This worked!!!
[plumwd_twitch_stream channel=”twitchchannelname”]