It supports AES-256 encryption, which is often used by creators to protect paid digital content.
You can search the ID "RJ140155" directly on DLsite.com to find the original product page, which will list the creator, cast, and description of the audio work. RJ140155.7z
The .7z extension indicates the archive format. Standard Windows or Mac tools sometimes struggle with this format, so you will need a third-party extractor: It supports AES-256 encryption, which is often used