If the “resize to fit” is NOT checked then it will ALWAYS be fine, no matter how you cropped.
The images don’t need to be cropped the same. If you crop them differently, then make sure the checkbox is off and it will still work. In this case the image dimensions won’t match between images but that is fine. The amount of empty space around each image can be different giving different dimension and it will work fine.
The issue is if you crop images differently and then turn ON the resize to fit to make them all the same size. What happens in that case is each image needs to scale by a different percentage to fit the new size. So some players get scaled more than others.
In your case, if you batch cropped in Lightroom and they are all the same exact crop then turning on the resize to fit won’t hurt anything because they all will get scaled by the same exact amount.
Hope this all makes sense