widgetize Simpla theme

Hello everyone, wanting to widgetize the beautiful Simpla theme, would appreciate all and any help.

Here is my site:
https://youcanhealwithenergy.com/

I followed these instructions:
https://automattic.com/code/widgets/themes/

with the Simpla Theme:
https://ifelse.co.uk/simpla

I made the changes as suggested. However, under Appearance-> Widgets I still get:

“No Sidebars Defined”
The theme you are currently using isn’t widget-aware, meaning that it has no sidebars that you are able to change. For information on making your theme widget-aware, please follow these instructions.”

Can anyone suggest what I can try now? I can put the code I used here if that would help. I appreciate your time and attention very much.
thank you!!
Diana