MTS Theme Builder

I just purchased the MTS Theme Builder and am getting an error message while trying to validate the licence. I have tried this both locally and on a dev server where we have SuiteCRM installed, both version 7.13.1. I followed the instructions for installing and did the quick repair and rebuild.

Nothing happens when we validate and this shows up in the browser console hinting at a 500 server error:

POST http://localhost:8080/index.php?module=MTS_ThemeBuilder&action=outfitterscontroller&to_pdf=1 500 (Internal Server Error)
VM272:1 Uncaught SyntaxError: Unexpected end of JSON input
    at parse ()
    at Function. (sugar_grp1_jquery.js?v=wAIzmwX0Pau3jMZKC6fzEg:6:3110)
    at e. [as parseJSON] (sugar_grp1_jquery.js?v=wAIzmwX0Pau3jMZKC6fzEg:6:1566)
    at Object.error (index.php?module=MTS_ThemeBuilder&action=license:1101:54)
    at c (sugar_grp1_jquery.js?v=wAIzmwX0Pau3jMZKC6fzEg:2:28327)
    at Object.fireWith [as rejectWith] (sugar_grp1_jquery.js?v=wAIzmwX0Pau3jMZKC6fzEg:2:29072)
    at l (sugar_grp1_jquery.js?v=wAIzmwX0Pau3jMZKC6fzEg:2:79926)
    at XMLHttpRequest. (sugar_grp1_jquery.js?v=wAIzmwX0Pau3jMZKC6fzEg:2:82355)

Jumping in to the server logs, this shows up:

suitecrm-suitecrm-1  | [01-Mar-2023 23:04:47 UTC] PHP Fatal error:  Uncaught Error: Non-static method SugarOutfitters_API::get_default_payload() cannot be called statically in /bitnami/suitecrm/modules/MTS_ThemeBuilder/license/OutfittersLicense.php:516
suitecrm-suitecrm-1  | Stack trace:
suitecrm-suitecrm-1  | #0 /bitnami/suitecrm/modules/MTS_ThemeBuilder/license/OutfittersLicense.php(223): SugarOutfitters_API::call()
suitecrm-suitecrm-1  | #1 /bitnami/suitecrm/modules/MTS_ThemeBuilder/license/OutfittersLicense.php(175): MTS_ThemeBuilderOutfittersLicense::doValidate()
suitecrm-suitecrm-1  | #2 /bitnami/suitecrm/modules/MTS_ThemeBuilder/outfitterscontroller.php(17): MTS_ThemeBuilderOutfittersLicense::validate()
suitecrm-suitecrm-1  | #3 /bitnami/suitecrm/include/MVC/View/SugarView.php(824): include_once('...')
suitecrm-suitecrm-1  | #4 /bitnami/suitecrm/include/MVC/View/views/view.classic.php(72): SugarView->includeClassicFile()
suitecrm-suitecrm-1  | #5 /bitnami/suitecrm/include/MVC/View/SugarView.php(210): ViewClassic->display()
suitecrm-suitecrm-1  | #6 /bitnami/suitecrm/include/MVC/Controller/SugarController.php(432): SugarView->process()
suitecrm-suitecrm-1  | #7 /bitnami/suitecrm/include/MVC/Controller/SugarController.php(363): SugarController->processView()
suitecrm-suitecrm-1  | #8 /bitnami/suitecrm/include/MVC/SugarApplication.php(101): SugarController->execute()
suitecrm-suitecrm-1  | #9 /bitnami/suitecrm/index.php(52): SugarApplication->execute()
suitecrm-suitecrm-1  | #10 {main}
suitecrm-suitecrm-1  |   thrown in /bitnami/suitecrm/modules/MTS_ThemeBuilder/license/OutfittersLicense.php on line 516

Please investigate.