The itch.io version of this software was able to download from R18 before they shut down. However, now that they no longer exist it doesn't do that anymore. The Patreon edition (still being developed) has the ability to place-shift from `dmm.co.jp`, provided you have a valid licence / entitlement for it.
Before you make any decisions, I suggest you read the project page carefully to see if ether of these versions is the right choice for you.