what is this large white plug of which you speakDoes the window open and close in normal operation. I too did mine this weekend and at first it worked perfect but today it didn't drop on opening door. I took the panel off and noticed the large white plug that was compressed when I fitted it has opened up. When you re compress it the windows opens slightly when the door is opened. Not sure if this will help you but that is What has happened to mine.
I have not seen the white holder like that before, maybe the clip on it is for transportation of it, and maybe the clip should be removed or it may clip into place again and stop it working properly, hope this helps