register theme problem

need help

I just buy DOR theme and installed it on my local Mac system using MAMP
everything seems to work BUT when I try to register my theme in order to Import demo content.
it doesn’t work, bellow the error message:

[03-Oct-2020 18:33:02 UTC] PHP Fatal error: Uncaught Error: Cannot use object of type WP_Error as array in /Applications/MAMP/htdocs/wp-content/plugins/dor-core/core-dashboard/core-dashboard.php:176

Stack trace:
#0 /Applications/MAMP/htdocs/wp-content/plugins/dor-core/core-dashboard/core-dashboard.php(137): DorCoreDashboard->register_purchase_code(‘purchase_code=a…’)
#1 /Applications/MAMP/htdocs/wp-includes/rest-api/class-wp-rest-server.php(1050): DorCoreDashboard->purchase_code_registration(Object(WP_REST_Request))
#2 /Applications/MAMP/htdocs/wp-includes/rest-api/class-wp-rest-server.php(376): WP_REST_Server->dispatch(Object(WP_REST_Request))
#3 /Applications/MAMP/htdocs/wp-includes/rest-api.php(339): WP_REST_Server->serve_request(’/dor-core/v1/re…’)
#4 /Applications/MAMP/htdocs/wp-includes/class-wp-hook.php(287): rest_api_loaded(Object(WP))
#5 /Applications/MAMP/htdocs/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(NULL, Array)
#6 /Applications/MAMP/htdocs/wp-includes/plugin.php(544): WP_Hook->do_action(Array)
#7 /Applications/MAMP/h in /Applications/MAMP/htdocs/wp-content/plugins/dor-core/core-dashboard/core-dashboard.php on line 176

I’m wrigting from France
thank you for any help or idea

Please get in touch with the author of the theme to get support: