Here is an example drush command for downloading the matching SDK. This drush command would be run from the root of the Drupal project.
drush make sites/all/modules/contrib/awssdk/awssdk.make ./ --no-core
All versions prior to 7.x-5.0 (i.e. 7.x-4.8 and below) correspond to the AWS SDK version number.
4.x -> 1.4.x
3.x -> 1.3.x
2.x -> 1.2.x
|SDK Version||Module Version|
|>= 1.5.x.x; < 1.5.4.x||7.x-5.1|
|>= 1.5.x.x; < 1.5.4.x||7.x-5.2|
The following versions contain bugs that do not allow them to work properly.
To use AWSSDK version 2, refer to https://www.drupal.org/project/awssdk2