Hi there!
If you check out the `README.txt` you can find all the information you need for Patreon. As for downloaded video files, *.dcv files from R18 are not supported as that website is no longer running and their licence servers are long dead. In addition, the secrets they use to secure videos are different than DMM, so cross decryption would be impossible. The only alternatives you have is to re-purchase all your titles on DMM with the Download option, or subscribe to one of their premium channels which allow downloading videos.