At this time our Amazon connections do not offer the ability to log in with or grant resources using IAM within Alteryx Designer.
The use of IAM has reviously been submitted to our Ideas page on the Community. I would encourage you to submit your use case on the mentioned post for adding this functionality and staring it. Our developers look to the Ideas page to see what users are asking for and suggestions for Alteryx. Be sure to share the link wit your colleagues so they may star the post and and their use cases, thoughts, or suggestions as well.
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