First, of all the tools installed to a folder structure compliant with the auto-import support in PowerShell version 3 or higher, so Import-Module is not needed.
It does however require that the PSModulePath update the installer performs takes effect, and we've noticed that on some systems you need to reboot after install.
Looking at PSModulePath you should see something like this (excuse wrapping):
PS C:\> ls env:PSModulePath | fl
Name : PSModulePath
Value : C:\Users\userid\Documents\WindowsPowerShell\Modules;C:\Program
Files\WindowsPowerShell\Modules;C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules\;C:\Program Files (x86)\AWS Tools\PowerShell\
If so, try restarting your machine and then open a shell prompt and see if Set-AWSCredentialsbecomes available.
Hope this helped!