Particular Case of RAR Password Cracking

[traf0]

Use free tools, they are more flexible
First use rar2john from John The Cracker jumbo package to get the hashes. With the hashes listed in a file you can start cracking them with john or hashcat .
In your case the "Wordlist + Rules" option is needed: c Capitalize the first letter and lower the rest
Google for a good dictionary or use those from SecLists.

More:

https://hashcat.net/wiki/doku.php?id=rule_based_attack
https://hashcat.net/wiki/doku.php?id=hashcat
https://github.com/danielmiessler/SecLists/tree/master/Passwords

Regarding "50% of the files contain a file which name contains this password.", you can create a list of them using easy bash script like:

for i in $(ls | grep .rar); do unrar l $i | grep "*" | awk '{ print $6}'; done