I only have InfoSWMM and it is turned on, screenshots below
Extension is on but toolbar is greyed out.
What is the version of ArcGIS that you are currently using?
Is InfoSWMM a third party tool?
It looks like you may not have any data that is compatible with the extenson in the Map
Given it looks like the extension is third party - I woulld look at their instructions to see what data is requried to make the tools operate
Retrieving data ...