Hi,
currently, our products works ok with joomla 3, for joomla 4 we need to make some changes.
So, if you want to add some php code you can add it in your form->Advanced->More options->Form pieces/Submit pieces.
If you want to add some javascript code, then you can add it in actionscript of each field (field->Advanced->Actionscript), or in form->Advanced->More options->Scripts
Here is documentation:
crosstec.org/en/support/online-documenta...ript-and-pieces.html
Regards,
Tihana