HI @Walmag Castro S ,
I trust you are doing great.
Please find the modified script as given below :

// Code to run without 'onclick'
// Ensure call to server-side function with no browser errors
if (typeof window == 'undefined') {
    runServer();
}

// Server-side function
function runServer() {
    // CONFIGURATION ITEM
    var ciGR = new GlideRecord('cmdb_ci_business_app');
    ciGR.addQuery('name', current.cmdb_ci.name);
    ciGR.query();

    // CATEGORY AND SUBCATEGORY
    var tableGR = new GlideRecord('dl_u_assignment');
    tableGR.addQuery('category', current.category);
    tableGR.addQuery('subcategory', current.subcategory);
    tableGR.query();

    // Set the workflow to false to avoid unnecessary actions
    current.setWorkflow(false);

    if (current.contact_type == 'redphone') {
        current.assignment_group = gs.getProperty('xpto.GROUPS.xxx');
        current.assigned_to = '';
        gs.addInfoMessage('Assignment Group will be set to: ' + current.assignment_group);
    } else {
        if (ciGR.next()) {
            if (ciGR.support_group != '' && current.assignment_group != ciGR.support_group) {
                current.assignment_group = ciGR.support_group;
                gs.addInfoMessage('Assignment Group will be set to: ' + current.assignment_group);
            } else if (current.assignment_group == ciGR.support_group) {
                gs.addInfoMessage('Assignment Group already correctly assigned.');
            } else {
                if (tableGR.next()) {
                    if (current.assignment_group != tableGR.assignment_group) {
                        current.assignment_group = tableGR.assignment_group;
                        gs.addInfoMessage('Assignment Group will be set to: ' + current.assignment_group);
                    } else {
                        gs.addInfoMessage('Assignment Group already correctly assigned.');
                    }
                } else {
                    gs.addInfoMessage('No Assignment Group.');
                }
            }
            current.assigned_to = '';
        } else {
            if (tableGR.next()) {
                if (current.assignment_group != tableGR.assignment_group) {
                    current.assignment_group = tableGR.assignment_group;
                    gs.addInfoMessage('Assignment Group will be set to: ' + current.assignment_group);
                } else {
                    gs.addInfoMessage('Assignment Group already correctly assigned.');
                }
            } else {
                gs.addInfoMessage('No Assignment Group.');
            }
        }
    }
}