If this is part of a movie, software, or audiobook, it is helpful to list the total number of parts (e.g., "Part 07 / 12").

If you created the RAR file, mention if it has a "Recovery Record" (záznam pro opravu dat), as this is highly valued in file-sharing communities.

g., more professional or more casual) for a specific platform?

Use "Code" blocks for links and passwords to make them easy for users to copy.