To transcribe audio/video from CDs or DVDs, you want to first convert the content on the CD or DVD into a wav, mp3 or mp4 file on your computer. You can then upload the converted files into Transcribe to convert them into text.
You'll find many tools online to help you convert CDs / DVDs into wav / mp3 / mp4 files. We'd recommend VLC Player which is free. Here's an article on how to do this: https://www.techwalla.com/articles/how-to-rip-cds-with-vlc.
Once you get the converted audio file from VLC player, you want to then click on "New Automatic Transcription", and then upload this file as usual.