Because this software is old, you cannot download it from the official ManyCam website (they now serve v8). You will need to find a third-party archive. Always scan any downloaded .exe file with Windows Defender or VirusTotal before running.
If your webcam is not detected:
ManyCam 3.0.80 introduced better handling of resolutions. Prior to this, virtual webcams often struggled to push a decent picture. This version allowed users to upscale their video output, making it compatible with the growing demand for HD streaming on platforms like YouTube and Twitch. The ability to define custom resolutions was a technical godsend for early broadcasters who needed to fit their streams into specific aspect ratios. manycam 3.0.80