S3 bucket permissions needed to access with WinSCP

We have a S3 bucket with a vendor that setup us to only send files too.

It works with the CLI but I can't get it work with WinSCP no matter how much I try and the vendor is being unhelpful giving us the we do not work with 3rd party tools response.

Can anyone tell me the Minimum Permissions WinSCP needs to put to a subdirectory in the bucket or even just access it? I get access denied on the open and I can't even get the GUI to connect to test the paths for script.

You might need to set the SessionOptions.RootPath:
How to connect to a server that does not allow an access to the root path?

If you need further help, please post session log file.

Oops Sorry I was already doing that. I will attach a log and this is what I think is the problem I'm pretty sure they only have this allowed and I think WinSCP needs more rights than this to connect and put. But since I can't see their end and they refuse to help. I'm trying to find the minimum rights WinSCP needs to open and put to a location.

You definitely need s3:ListBucket permission, probably also s3:GetBucketLocation.

Ok. I'll Try to get the vendor to add those and see if it works.

It's maddening cause if I could just get them to actually put in a little effort and look at some logs this would probably be solved in 5–10 mins but instead they want to be stubborn and lazy.