Are there open source extensions available? It isn't possible for me to purchase Spatial Analyst.
Did you also check
Conversion Toolbox > To Raster toolset > Feature to Raster.
I think this would work fine with all licensing level. Please verify.
Feature to Raster
Do you have ArcGIS Desktop Advanced License? Then you can do it without SA/3DA extension.
Polygon to Raster (Conversion Tools)
I get a popup that says I do not have the "necessary license to execute the selected tool," so I suppose I do not.
In that case, if you want to get your hands on an open-source software QGIS (Vector to Raster tool)...
In ArcMap, one way to check on the license level you have:
Chris Donohue, GISP
Thank you this works well for what I am doing
Retrieving data ...