add error message to condition

Yes, I Would like to add error message in a condition

Can you please explain further your requirement for the error message condition?

Is this error for Card Forms or the Classic Layout?

Do note that the form has Form Warnings that can be found in your Settings>Form Settings

that I can add some custom popup error message, like that must set minimum 2 checkboxes to Input Table

You can customize your error messages in the Form Warnings.

To clarify, is this error condition specific with the Input Table?

Can you please explain further your requirement regarding your pop up message so that we can forward it to our developers as a feature request?

Looking forward for you response.

In forms required messages it has At least one field required. only, but if input table currently not supporting minimum or maximum required so i would like to create some custom windows that can be like a popup and block if possible or to show him some warning

You can try using a Text field (add the error message) and use the Show or Hide condition. For more information about the Show or Hide condition, please check this guide: 

How-to-Show-or-Hide-Fields-Base-on-User-s-Answer

Please try it and let us know if that's what you're looking for.

Also, have you tried the Built-in Required field of the Input Table?