SaaS ALM QC edition 12.00, 12.20, 12.50
When creating new domains on the QC edition of ALM on SaaS you must first allocate licenses to the domain before using said domain. The license allocation will not let you allocate ALL licenses to each domain, but only part of your licenses.
You have to either use a single Domain for all projects, or split the licenses up e.g. if you have 10 total full licenses, you can allocate 5 to domain "A" and 5 to domain "B".