As described on https://www.ibm.com/support/knowledgecenter/SSQL82_9.5.0/com.ibm.bigfix.doc/Platform/Config/c_airgap_tool_Req.html,
the Airgap tool is platform dependent, but the AirgapRequest.xml (for extraction usage only) and AirgapResponse files are not.
You can download Airgap tools for Windows from https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/Tivoli%20Endpoint%20Manager/page/Airgap%20Tool.
It is suggested you use the identical version of airgap tool on Windows computer as with RedHat computer. Extract downloaded file on Windows computer.
To use extraction usage, you create AirgapRequest (tar) on your RedHat server. Then extract that tar file and only copy AirgapRequest.xml to the folder of the Windows computer and then run Windows version of Airgap tool.
When AirgapResponse is created on Windows computer, copy that to RedHat computer where RedHat Airgap tool resides (the folder you have extracted your tar) and then run the Airgap tool on RedHat as described in the Knowledge Center.