How to export a Theme

Hi,
Can someone suggest me the best way to export a Theme from another WP site and then I should be able to import it in my site?

I have tried https://wordpress.org/plugins/wp-clone-template/ but no luck.
I have even posted questions on https://wordpress.org/support/topic/i-dont-get-an-option-to-select-the-theme-to-export?replies=3 but no reply.

Any suggestions would be welcomed.

Thanks, AG.