While we work to resolve the Twitter API integration, here are the steps to manually stream to your Twitter feed.
Twitter Media Studio
You will need access to Twitter Media Studio, which requires a verified Twitter account.
Once you have access, the steps to setup a broadcast are detailed in Twitter's support article:
Note that both Twitter and Solo support RTMPS, so you can optionally use the RTMPS url.
Once you have a Broadcast setup in Media Studio, that will create a stream key for you to use.
Use the Generic Destination Type
In Solo Portal, you can now use the Generic destination type with the stream key you got in the step above, and the RTMP or RTMPS url provided by Twitter Media Studio.
With both the Broadcast setup in Twitter Media Studio and using the Generic destination type in Solo Portal, you can start streaming and go live to Twitter.