Last time I was involved in installation of SAP stuff is already a few years ago but if my memory serves me well you need to download the SAP libraries from the SAP portal. The SAP transports are part of the downloads provided by Informatica.
So your SAP administrators who will have an account on the SAP portal can download the supported version for you.
Hope this helps
You have to download SAP NW RFC SDK files from SAP Support portal.
For cross-checking the library files refer to Powercenter help guide:
PowerExchange for SAP NetWeaver User Guide > Getting Started with PowerExchange for SAP NetWeaver > Installing and Configuring PowerExchange for SAP NetWeaver > Installing the SAP NetWeaver RFC SDK Version 7.50 Libraries.