I cannot recall a setting within ipab. Try re-starting the process again and see if it makes a difference.
What you have done should have worked but I can recall doing the same thing and experiencing the same problem. My username and/or password weren't recognised and nothing happened! In the end, I flashed my box with a different build/image and manually added my iptv sub using 'putty'.
Failing that, I would send a message to your provider explaining the problem you are experiencing. Then ask him to send you a m3u file (which will include your username & password) instead which you can ftp over. Your provider may not send over a m3u to you however but instead send over a different format (such as a .ipk file for the xtreamtv plugin) but that should also work. We can help you on here if you go down that route.
Hopefully, it won't come to you having to reflash your box with another build and there may be someone on here who is more familiar with ipab and know ways around the problem. I will keep my fingers crossed for you!
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