1. For upgrade download Upgrade package and Copy upgrade files from that zip (Large Upgrade package)
2. To add the Language files just download the files from the following URL :
https://download.simplemachines.org/index.php?languages
3. The files should be the latest SMF version
4. Download the utf-8 files for all Languages (utf-8 is not available for 2.1.x hence we download default language files)
5. Copy all the zip files to /languages folder
6. Rename if language is not in "language.zip" format from "smf_version_language.zip"
7. PHP REQUIREMENT LINK: https://wiki.simplemachines.org/smf/SMF2.1:Requirements_and_recommendations
8. Uncheck "Allow Stat Collection" in manual installation. This can be changed from admin->configuration->server settings->general->Allow Stat Collection