Because the original is not compatible with the new version I add support for ACF 5 and improved the CSS a litlle bit.

This version works only with ACF 5 and works in Tabs as well.

For each column add a Column Field to your field group and define the width for this column. You can select between 1/2, 1/3 and 1/4 columns. To close a row you have to add a Column Field with the value 'Reset'.

This field group with columns

will show this on page/post edit screen

Thanks to LightboxDev for the idea and the basics.