If you want to add an ActiveX control to a form (UserForm) in Excel/Word VBA, you should open the Toolbox and add the ActiveX control icon to it first. After that you can drag the control onto the form surface, resize it, change its properties, etc. You can find numerous examples of doing this in the Internet (for example, video lessons on YouTube).
My idea was to check whether iGrid ActiveX can be instantiated on that 'problem' pc in general, i.e. in other apps. If so, then it can be a specific problem of Microsoft Access.
I have no other ideas what it could be at the moment. Perhaps, you can ask why you can't add an ActiveX control in specific forums for Access developers. Keep us informed, please, especially if you find an answer or solution.