How do Crowdin calculate the usage for OTA?

Hello, how do you calculate the usage for OTA? I find this feature to be pretty interesting but I’m wondering about the price? Don’t see anytihing in the knowledge base

If you have up to 1M requests and 10GB of data transfer, the feature will be free for you. If more than paid but price vary.

More info about price of CDN in Crowdin official website, Add-ons section: