OpenCart module not working on 2.3.0.2

[wetory]

Hello, I know that this extension has been deprecated, but maybe you can help me. I've tried to implement it to my customer's e-shop using AJAX version. But it is not working. Below is repeatedly raised error in console:

Uncaught ReferenceError: validateAllFields is not defined
overrideAQCValidate https://qa.x-wetory.eu/hmvp-2302/index.php?route=checkout/checkout line 5 > injectedScript:18
setRequiredOpt https://qa.x-wetory.eu/hmvp-2302/index.php?route=checkout/checkout line 5 > injectedScript:63
setTimeout handler*fn https://qa.x-wetory.eu/hmvp-2302/index.php?route=checkout/checkout line 5 > injectedScript:131
addHooks https://qa.x-wetory.eu/hmvp-2302/index.php?route=checkout/checkout line 5 > injectedScript:135
each https://qa.x-wetory.eu/hmvp-2302/catalog/view/theme/materialize/js/script.js:5
each https://qa.x-wetory.eu/hmvp-2302/catalog/view/theme/materialize/js/script.js:5
addHooks https://qa.x-wetory.eu/hmvp-2302/index.php?route=checkout/checkout line 5 > injectedScript:124
main2 https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:677
jQuery 5
main2 https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:672
main https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:663
onreadystatechange https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:723
include https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:714
main https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:662
https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:765
onreadystatechange https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:723
include https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:714
https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:762
https://www.zasilkovna.cz/api/0eea0823503d2a42/branch.js?callback=addHooks:767

Any help appreciated. Thank you in advance.