Image transfer from multiple DLSR cameras using USB hubs and cables

Hello, I am working on a photogrammetry-based 3D scanner using 40 Canon 100D cameras. For triggering and powering the cameras, I am using ESPER Trigger and Power Boxes, which is working fine. The problem I am facing is related to the file transfer. I have connected all these cameras to a single PC (Windows 10) using six 7-ports USB 3.0 hubs (externally powered). My PC has three USB 3.0 ports and 4 USB 2.0 ports. When I connect all USB hubs to the PC, I get an error that the USB device is not recognized, connecting 30 cameras at one time (sometimes less or more and I don’t understand why). After doing some research, I found that an extra USB 3.0 PCI-E may work, but unfortunately, it didn’t. Today, I attached two 7-ports PCI-E cards to PCI slots on the motherboard and attached all those USB hubs to these newly added PCI-E cards, which now gives me error that the maximum number of USB hubs have surpassed. In fact, each PCI-E card reads only two cameras per USB hub, less than the original USB ports I had before on my motherboard.
Can someone please suggest to me how to connect 40+ cameras to a single PC (Windows 10) using USB hubs? I know this is the limitation on the hardware side but there are many photogrammetry scanners out there using 100+ cameras. How do they control cameras for file/image transfer?