My custom field is named ExternalURL (Advanced Custom Fields 4.4.12)
I’d really appreciate if anyone knew what to do :/
All the best!
]]>https://www.advancedcustomfields.com/resources/get_field/
You’d then wrap the post thumbnnail with it, something like
echo '<a href=", get_field( 'externalurl' ), '">';
the_post_thumbnail( 'thumbnail' );
echo '</a>';
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