How Can I Create Login/Register button outside Navigation bar?

Log into your site
Go to Pages -> The page you want to show up this button – In this tutorial, I will add it to the Homepage area.
Click on Add New Shortcode -> Select Call To Action shortcode (I’m using King Composer page builder, You will find the same shortcode if you are using Elementor or WP Bakery Page Builder)
Complete all settings of this shortcode. Next, scroll down to Custom Class setting, Add wilcity-trigger-login-button to this field if it’s Login button and wilcity-trigger-register-button if it’s Register button
Finally, Insert this shortcode to Editor.

Elementor

If you are using Elementor pro and You want to use Custom Header feature, We recommend referring to How to add How can I add Wilcity Menu Items to Elementor Header