Unable to activate Amazon S3 add-on on Download Manager Free

Hello,

we bought a license of the Amazon S3 add-on.
Afterwards, we downloaded it and we extracted into our plugins folder.
The plugin was being listed as non-active in the plugin list, as expected.
Unfortunately, when clicking on “Activate”, WordPress complained about the lack of some S3 configs (region and version).

Where am I supposed to set them up? I’m not seeing any guidance neither on the forum nor by looking at the code: I just see the possibility of making the ‘AWS_ACCESS_KEY_ID’, ‘AWS_SECRET_KEY’, ‘AWS_SECRET_ACCESS_KEY’ and ‘AWS_PROFILE’ available by means of the $_SERVER superglobal, but I see no way to setup the aws region and API version.

Thank you for your attention