Working with current version of WP

I have been having some issues where, the first time that I use shortcode, it works and then it never does. I installed it in the normal way and I saw the warning I show at the bottom regarding version 4.3.0  not having been tested with the my version of WordPress, which is the latest, version: 5.7

When it ‘fails’, the shortcode is essentially shown as text in the webpage.  
When I use the [wp-invoice] shortcode, I can see that no matter what the options are, a whole page is taken up? 

Do you have an alternative plugin I can test or plans to test with WP 5.7? 

The page I need help with: [log in to see the link]