As far as I can tell in the Mac version of the software; the only option is to add the access key and secret key. Unless I’m missing something.

I get a box that pops up and says "Connection Failed. Check your credentials." There is a button that says details and when I press it, another small box shows an access denied message. I can send a screenshot tomorrow if you want to see what it looks like.

One thing I have noticed is that the access key and secret key work with the windows version of the software. The only difference seems to be that after I add the access key and secret key I have to press the Add External Bucket and put the path for the bucket to appear.

Yes