We are doing pin mux for phyCORE-i.MX6UL, so I downloaded the pin mux tool from the below link which is i.MX Pins Tool Verions 3.0.2:
But the below ".mex" file is made for i.MX Pins Tool Verions 2.0:
So, could please share the Download link for i.MX Pins Tool Verions 2.0.
as stated in the dialog window in your screenshot, .mex file made in v2.0 can be opened in v3.0 without a problem.
If you have no other reason to use v2.0, it is recommended to use the latest version of the tool.