According to the documentation, you should display a field like:
<p><?php the_field('field_name'); ?></p>
Change your get_field
to the_field
:
<span class="c_f"><a href="https://wordpress.stackexchange.com/questions/131004/<?php the_field("field2_link'); ?>"><?php the_field('field1_details'); ?></a></span>