If you don’t have an account on https://www.telcor.ro/ yet, just contact them through their website and they will provide you with a username, password, and sender ID that you’ll need to add to the plugin fields.
With regard to the Client ID, the API documentation states: “represents a unique ID provided by you, and that is used to uniquely identify SMS messages posted in the platform Telcor“.
You can, therefore, set the value you prefer by paying attention not to leave the field empty since this data is mandatory.