Minor I performed a clean install of Jenkins 2.33 (and 2.37) into Windows and although the S3 plugin installed, the sub-section of "Configure System" for "Amazon S3 Profiles" did not appear. There were no errors in the logs; all plugins loaded successfully.
In order to get the credential section to appear, I had to rip out version 2.x and install 1.609. Once that was done I was able to configure my S3 profile. Updating to 2.x after the fact did not break this - it is still working properly.
It seems as though there's a requirement buried somewhere in 1.609 that gets carried forward after an upgrade but that isn't present in a clean install of 2.x. Either the plugin needs to be updated to work correctly in a clean build, or whatever holdover is present needs to be brought forward to the 2.x series.
The INFRA project in JIRA is for Jenkins project infrastructure tasks only, please do not file tickets there.