Chris, that response from PMI support doesn’t really add up. The PMI website should be accessible from any standard browser, and in my experience, I’ve always been able to access my purchased courses through the "My Library" section regardless of the device I’m using. At the very least, course access should not be restricted based on whether it's a personal or work computer, unless your organization has increased its firewall or security protocols. Even then, a platform like PMI should be designed to function within common enterprise environments, especially given its focus on professional development and corporate training.
I know it’s not an ideal solution, but I’d suggest trying to contact PMI support again. In many cases, if you speak with a few different representatives, you’ll get a variety of responses and occasionally, you might get someone who actually understands the issue and can offer a real solution. It can be frustrating, but sometimes persistence is the only way to get past the initial unhelpful responses.