The documentation for past versions of FME Flow (formerly FME Server) can all be found online.
FME Flow 2023
FME Server 2022
FME Server 2021
FME Server 2020
FME Server 2019
FME Server 2018
FME Server 2017
FME Server 2016
FME Server 2015
FME Server 2014
FME Server 2013
Links to the downloads and documentation for past versions of both FME Form (formerly Desktop) and FME Flow (formerly Server) can also be found on the downloads page:
https://www.safe.com/support/downloads
On the downloads page, click the dropdown arrow next to the current version to access past versions.