AWS Authorization Error When Creating New Partner Contact Center for Voice in Salesforce

I am trying to create a New Partner Contact Center for Voice in Salesforce, but I am encountering the following error:

Hello,

Something went wrong when you tried to make a change in Service Cloud Voice. Here are the details from Amazon Web Services:

AWS error message: User: arn:aws:iam::111111111111:user/ScvIntegrationUser is not authorized to perform: sts:AssumeRole on resource: arn:aws:iam::111111111111:user/xxx

Thank you,
Salesforce Service Cloud Voice

It looks like an AWS IAM permission issue related to the sts:AssumeRole action. How can I resolve this authorization error and properly configure the permissions for Service Cloud Voice integration with AWS?

Any guidance or steps to fix this would be appreciated!