The default space suggested for the root, temp, and log dbspaces is about 1 MB per user.
The default for the ccm dbspace it is about 2 MB per user. For the default 40 users, the total is about 220 MB. For each chunk file, the limit is 4 TB.
This estimate is only a rough estimate for the initial database chunk. In general, generously allocate dbspace to allow for future growth.