A CompanyID is a unique key for your company in Acubiz. CompanyID are used to log into Acubiz Apps and can be found in several ways:
Go to My settings via gear button in the upper right corner. Here you can find your CompanyID under the item Acubiz Apps.
In the area Login information you can find your FirmaID / CompanyID
Alternatively, it can be found in your browser's address bar: