At the end I found my mistakes and solutions
. When selecting “File Upload” I didn’t select Multi File Upload so I didn’t see the button, after that the design of the selection changed, but I didn’t like the button because it was long, so I added this code
body .gform_wrapper .gform_body .gform_fields .gfield .ginput_container_fileupload .gform_button_select_files {color: red;
width: 220px !important;
color: white !important;
background-color: #B22234 !important;
border-radius: 8px !important;}
Now it looks like this
