I should also mention tools like WinRAR for extracting RAR files, or 7-Zip as a free alternative. Then, steps like scanning the extracted files with antivirus before installation. Highlight the importance of reading the contents and understanding what's being installed.

Putting this together, the user is likely trying to install software they found on an illegitimate site, perhaps a streaming tool, which comes in a RAR file. They want to open it, play some content, but run into issues. The CAP part is unclear but could be part of the file type or a step in the installation process.

I need to address the potential risks involved in opening files from unknown sources, especially if they're downloading from a site like 51Scope. It might be best to advise against such activities and instead suggest legal alternatives. However, since the user is asking for installation instructions, I should provide a general guide on how to handle RAR files and install software securely, but also emphasize the risks.