The Orion instance at FI-LAB uses OAuth authentication. Thus, you need to include a valid X-Auth-Token HTTP header in your requests to Orion.
Your application should implement OAuth and negotiate with the security framework a valid token for that. However, for debug or quick testing you can use the following shell script in order to get a fresh X-Auth-Token:
https://github.com/fgalan/oauth2-example-orion-client/blob/master/token_script.sh
The script will ask you your FI-LAB user and password.
Please, have a look to https://wiki.fi-ware.org/Publish/Subscribe_Broker_-_Orion_Context_Broker_-_User_and_Programmers_Guide#FI-LAB_context_management_platform to get more detail on Orion FI-LAB deployment.
EDIT: the recently published Orion Quick Start guide also includes an example on how to use the token_script.sh script that can be useful.