Translate wordpress plugin

I have a small problem, I am trying to translate a plugin using

wpml locotranslate polylang

Try moficar .po .mo files, but nothing, I can not get the plugin to change language, according to the developer is easy to translate

/**
 * Creating widget front-end - This is where the action happens.
 * @param array $args
 * @param array $instance
 */
public function widget( $args, $instance ) {

    $title  = ( isset( $instance['title'] ) && ! empty( $instance['title'] ) ) ? $instance['title'] : __( 'Monthly Mortgage Payments', 'mc' );
    $title  = apply_filters( 'widget_title', $title );

    $mc_total_amount_label      = ( isset( $instance['mc_total_amount_label'] ) && ! empty( $instance['mc_total_amount_label'] ) )          ? $instance['mc_total_amount_label']    : __( 'Total Amount', 'mc' );
    $mc_down_payment_label      = ( isset( $instance['mc_down_payment_label'] ) && ! empty( $instance['mc_down_payment_label'] ) )          ? $instance['mc_down_payment_label']    : __( 'Down Payment', 'mc' );
    $mc_interest_rate_label     = ( isset( $instance['mc_interest_rate_label'] ) && ! empty( $instance['mc_interest_rate_label'] ) )        ? $instance['mc_interest_rate_label']   : __( 'Interest Rate', 'mc' );
    $mc_mortgage_period_label   = ( isset( $instance['mc_mortgage_period_label'] ) && ! empty( $instance['mc_mortgage_period_label'] ) )    ? $instance['mc_mortgage_period_label'] : __( 'Mortgage Period', 'mc' );

    // before and after widget arguments are defined by themes
    echo $args['before_widget'];

    if ( ! empty( $title ) ) {
        echo $args['before_title'] . $title . $args['after_title'];
    }
    ?>
    <div class="mc-wrapper clearfx">
        <form id="mc-form" action="#mc-form">
            <p>
                <label for="mc-total-amount"><?php echo esc_html( $mc_total_amount_label ); ?></label>
                <input type="number" name="mc_total_amount_label" id="mc-total-amount" min="1" class="required" placeholder="<?php echo mc_get_option( 'mc_currency_sign', 'mc_settings', '$' ); ?>" value="<?php echo apply_filters( 'mc_total_amount', null ); ?>"/>
            </p>
            <p>
                <label for="mc-down-payment"><?php echo esc_html( $mc_down_payment_label ); ?></label>
                <input type="number" name="mc_down_payment_label" id="mc-down-payment" min="1" class="required" placeholder="<?php echo mc_get_option( 'mc_currency_sign', 'mc_settings', '$' ); ?>">
            </p>
            <p>
                <label for="mc-interest-rate"><?php echo esc_html( $mc_interest_rate_label ); ?></label>
                <input type="number" name="mc_interest_rate_label" id="mc-interest-rate" min="1" class="required" placeholder="<?php esc_html_e( '%', 'mc' ); ?>">
            </p>
            <p>
                <label for="mc-mortgage-period"><?php echo esc_html( $mc_mortgage_period_label ); ?></label>
                <input type="number" name="mc_mortgage_period_label" id="mc-mortgage-period" class="required" placeholder="<?php esc_html_e( 'Years', 'mc' ); ?>">
            </p>
            <p>
                <input type="submit" id="mc-submit" value="<?php esc_html_e( 'Calculate Mortgage', 'mc' ); ?>">
            </p>
        </form>

        <!-- This div is holding output values-->
        <div id="mc-output" class="clearfix"></div>
    </div>

    <?php echo $args['after_widget'];
}

It would be very helpful for someone to help me:)

the answer with the solution wins a coffee / beer