A common business model for open source software is to give the software away (because it's open source) but charge for licenses that come with tech support, responsiveness to bug reports, etc. This is basically Red Hat's whole thing.
Conversely, and I don't know if this is the case with your particular program, it's not uncommon for software to be open source because it incorporates a bunch of existing open source code, so by GPL or whatever it has to be free as well. In these cases the company might try to downplay or obscure the fact, or not make it easy to build it yourself, because they want you to buy their version.
A common business model for open source software is to give the software away (because it's open source) but charge for licenses that come with tech support, responsiveness to bug reports, etc. This is basically Red Hat's whole thing.
Conversely, and I don't know if this is the case with your particular program, it's not uncommon for software to be open source because it incorporates a bunch of existing open source code, so by GPL or whatever it has to be free as well. In these cases the company might try to downplay or obscure the fact, or not make it easy to build it yourself, because they want you to buy their version.