If you're unable to find a free PDF, consider:
If you do obtain a copy, don't just read it. Quantum chemistry requires "pen and paper" learning. Work through the derivations in Chapter 3 and 4 manually; understanding the math behind the operators is the only way to truly grasp the chemistry of the electron.
"Introductory Quantum Chemistry" by A.K. Chandra has several key features that make it an excellent textbook: