What are the data limits (GB) per user and/or company?

There is a 10GB limit on the free version of Altium 365 and a fair usage policy is in place (https://www.altium.com/terms). If you want more than 10GB of cloud storage, purchase the Organizational Security Package. In the case where you are overusing the service and consuming resources on a level that is significantly above the average, we will work with you to figure out a solution.