Primer for importing WordPress content that includes ACF fields, using Really Simple CSV Importer plugin.

custom_csv_import.php

<?php

// Import function
function custom_csv_import($meta, $post, $is_update) {
    // Create containers
    $meta_array = array();
    $repeater_array = array();

    /*  It may help to list out the ACF fields you are populating
        Table Heading       ACF Key                 Repeater Fields
        =============       ==================      =================  
        sample_field        field_XXXXXXXXXXXX      N/A
        sample_field        field_XXXXXXXXXXXX      N/A
        sample_field        field_XXXXXXXXXXXX      ['link_type'], ['link_text'], ['link_url']
    */

    // Loop through CSV
    foreach ($meta as $key => $value) {
        if($key == '**YOUR_TABLE_HEADING**')
        {
            // Example of comma separated list (ACF select, check-box, etc.) - run before other fields
            $meta_array['**YOUR_ACF_FIELD_KEY**'] = preg_split("/,+/", $value);
            
        } 
        elseif($key == '**YOUR_TABLE_HEADING**') 
        {
            // Example of standard field
            $meta_array['**YOUR_ACF_FIELD_KEY**'] = $value;
        } 
        elseif($key == '**YOUR_REPEATER_FIELD_HEADING__1.1**') 
        {
            // If there is a value, add value to a repeater array (with field name as key)
            ($value) ? $repeater_array[0]['**YOUR_REPEATER_FIELD_NAME**'] = $value : false;
        }
        elseif($key == '**YOUR_REPEATER_FIELD_HEADING__1.2**') 
        {
            // If there is a value, add value to a repeater array (with field name as key)
            ($value) ? $repeater_array[0]['**YOUR_REPEATER_FIELD_NAME**'] = $value : false;
        }
        elseif($key == '**YOUR_REPEATER_FIELD_HEADING__2.1**') 
        {
            // If there is a value, add value to a repeater array (with field name as key)
            ($value) ? $repeater_array[0]['**YOUR_REPEATER_FIELD_NAME**'] = $value : false;
        }
        elseif($key == '**YOUR_REPEATER_FIELD_HEADING__2.2**') 
        {
            // If there is a value, add value to a repeater array (with field name as key)
            ($value) ? $repeater_array[0]['**YOUR_REPEATER_FIELD_NAME**'] = $value : false;
        }
        else 
        {
            // For basic fields(like post_title) run standard import
            $meta_array[$key] = $value;
        }
    }
    // Insert Repeater data
    $meta_array['**YOUR_REPEATER_ACF_KEY**'] = $repeater_array;
    return $meta_array;
}
// Hook into really_simple_csv
add_filter('really_simple_csv_importer_save_meta', 'custom_csv_import', 10, 3);