Hello Grezegorz, i was able to fix the problem and made a small tutorial for the use of mdb and symfony4 with webpack. perhaps this is usefull for other customers.

https://h2-invent.com/softwarenwicklung/implement-mdbootrap-in-a-symfony4-application-with-webpack/

Best regards Emanuel

Hello Grzegorz, I tried to create a snipet but it is not possible to generate one, becaue I use webpack to pack all my elements. I did it, as in this Thread described https://mdbootstrap.com/support/jquery/uncaught-typeerror-cannot-assign-to-read-only-property-exports-of-object-object/

//with this import the init is working:
import ('mdbootstrap-pro/js/bootstrap');

// with this import the init is working too, but at the first click on the select I get the 
error
import bootstrap from 'mdbootstrap-pro/js/bootstrap';

//This is my doc ready function
$(document).ready(function () {
    console.log('test');
    $('select').materialSelect();
    $('.pickadate').pickadate({
        format: 'dd.mm.yyyy',
        formatSubmit: 'yyyy/mm/dd',
    });

});

One more hint, I have bootstrap in the webpack imported as well, because other components in my application needs bootstrap as well. but if I delete the bootstrap in the webpack import then the later initialiation is woking as well.

so there must be a conflict in importing the bootstrap in the webpack and mdbootrap. I'm realy sad that mdb is not working as a normal webpack component because of the export error this would save me hours of work to solve this issue. I'm realy not happy with the theme until now. Especially because the freeversion worked as a webpack component.