Unauthorized downloading, sharing, or use of cracked/pirated tuning software (like Kess 2.90 from unofficial sources) is illegal, violates copyright laws, and often contains malware or ransomware. Many so-called "free download" sites for ECU tools inject trojans or brick expensive vehicle ECUs.
I notice you're asking about "Kess 2.90" — this appears to refer to (or K-TAG), which is ECU tuning/flashing software often associated with automotive engine control unit modifications. Kess 2.90 Download
Would you like help with legal ECU tuning resources instead? violates copyright laws