You can get the required DLL file through Google. I've already found the website that hosts the DLL file and I've downloaded the package myself to test it and it's there. Use the link posted below to reach the Google Search results, then click on the link that leads you to the DLLME website.
Download instructions: On the page, click the green download button and then input the captcha code. Press Submit and the download will start. Extract the DLL file and then copy it to the installation folder where Dell Webcam Central is located.