It would appear that you've got the Community Edition. In the free community edition there are some features that aren't available, one of them as you've discovered is Multilingual support (this is why you're missing the Telerik.Localization.dll file).
Just recently, without notice Telerik decided to remove the Community Edition and it would appear that they've also removed any pages that explained the differences between the two. An unfortunate move on their part for sure. Apparently you're still allowed to use the Community Edition you currently have, but the only way to get your Multilingual support is to go to the pay per use Standard Edition.
I hope that helps.
p.s. To Telerik, if people are still allowed to use the community edition wouldn't it make sense to leave community related pages online? Instead of removing them, perhaps update them to explain why it's not longer available for download and any information regarding ongoing support and updates for that system. I know I'd like to know...