Hi Greg,
Thank you for using Syncfusion products.
Our latest version Essential Studio v9.1 does support MVC3 . Since, MVC 3 works only in 4.0 framework(VS2010) the 9.103.0.20 assemblies won’t work in MVC3, because this assembly refers to 3.5 framework.
By default, ES v 9.1 version is shipped with MVC3. If you want to use it in MVC2 , you need to use our MVCVersionSwitcher from the utility folder. For more details, please refer to the following link
https://s3.amazonaws.com/files2.syncfusion.com/support/ASP%20MVC/MVCVersionSwitcher.docxPlease let us know if you need further clarification.
Regards,
Eswari S