The license on this project is pretty confusing. The license at the root of the project links to backend/cc/LICENSE.md which says you need a subscription license to use the code. Can you call it open source if you need a subscription license to run / edit the code?
Yes. Open source doesn’t mean free.
A common "trick" for commercial open source software is to use a copyleft license, which restricts redistribution as part of commercial products, and to offer a paid license to get around that.