I have access to the sde30 reader but it is greyed out in the list of availible writers. I found this article https://knowledge.safe.com/articles/358/arcsde-lib...
but I don't understand why the reader is available but not the writer, seems like the reader would need the sdk and dlls as well as the writer.
The only thing I can think of is that you have an FME Professional license, which allows reading of SDE but not writing. For writing you would need an Esri edition license or similar.
Check out this page for a full format listing and requirements: https://www.safe.com/fme/format-search
I see "Esri Legacy ArcSDE" allows reading with a Professional license, but not writing.