Register fields via PHP

Hi there,

I just created a blank theme with default configuration in order to register custom groups, following the documentation : https://www.advancedcustomfields.com/resources/register-fields-via-php/

Despite my efforts, I couldn’t register any groups.

JSON sync is working very well, as long as the admin.

Neither the generated PHP nor the code given in the documentation seem to work.

ACF v 5.9.4

Thank you for your help

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