With dedicated CAD converter like the INOVATE it should be possible to translate (convert) drawings in STEP/STP format to the default IronCAD format (*.ics). It seems ICS format is rarely supported in CAD software and no other converter is known to us that supports this format.
Convert ISO-10303 STEP product data to IronCAD 3D CAD file.
We found one software available in the database for this conversion.
Microsoft Windows software - convert step to ics on Windows
A 3D desktop CAD software
Convert from step file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.