When you run the Eikon API with a new Eikon ID which has not been used before, the "welcome screen" appears but it won't fit in the window. Therefore, it's not possible to continue. It looks like this:
Resolver not registered: react.asset.discussionTagsAsset
The workaround is to login with the new Eikon ID in the web version at http://eikon.thomsonreuters.com/login
If you click through the first pages, your Eikon account will now be ready to use with the Eikon API Proxy.
Permission Problem You need the session.valid permission to do that.