How to show custom value of created custom field?

Hello,

Can you please help me to show value of custom field in the front-end.

I’ve created custom field “category” which is shown in the wordpress dashboard in the car options. But I can’t make it work on the front-end to show it with this line as written on the plugin website:

<?php echo get_post_meta( get_the_ID(), ‘category’, true ); ?>