At the moment you can download data related to Analytics & API logs.
Downloading API analytics, you will get the following data columns: Client ID, Organization Name, First Name, Last Name, Email, Subscription ID, Subscription Status, Product Name, Total call count.
Downloading API logs, you will get the following data columns: Timestamp, Http Method, Resource Path, Path Parameters, Query Parameters, Headers, Body, Status Code, API ID, API Name, API version, Product ID, Product Name, Subscription ID, Group ID, Group Name.
Note that you will get less data in case you enabled the Privacy mode (Settings > API logs > Privacy mode). In that case, all Personal Identification Information will be removed.
There is no option to download data from the client section yet.
However, depending on the data you need, you can find it by downloading the data from the analytics and API logs sections. Let us know if downloading clients information is something you would like to see implemented, from the channel #general:feature-requests.