For radio button fields, you’ll need to add ['value'] or ['label'] after the variable to show either the value or label:
<a href="<?php echo get_permalink( $shopid['value'] ); ?>" class="button">See</a>
For testing, you’ll want to grab the object which will include the values and labels:
<?php
$shopid_obj = get_sub_field_object( 'cat_link' );
var_dump($shopid_obj);
?>
The above will spit out the array of your radio button field so you can see what’s there.
See more here: https://www.advancedcustomfields.com/resources/radio-button/
