ringtones plus garage band equals "the song could not be opened" Why?

Hi, guys.
I noticed the forums haven't been too too quiet, but I did some forum searches mainly on the subject of converting MP3 files into ringtones through Garage Band for iOS and I have the later version. I will soon be trading in my old iPhone SE for an iPhone XR, but wanted to know a few things. Can you still convert ringtone MP3 files through garage band? Also, I tried to do this, but what I did was export a ringtone from an MP3 file and it said, "The song could not be opened." I'm running iOS 12.1.4. Again, this is my SE we're talking about. I saved the MP3 file into my Apple files thingy under Garage Band file transfer, but why is the song not able to open? Ugh.
I was told to go to tracks view, but I am confused by the ringtone conversion I could have done there. Please note, I do not own a Windows or Mac, so can't use said windows or mac pc or computer to transfer the Ringtone completely. I even tried naming the ringtone with no spaces, no luck. Please help.
Beth

Forum: 

re: Ring Tones in Garage Band

Yes, I read all of the Google results about using Garage Band to create ring tones on an iOS device. I struggled to do this on my iPhone using voiceOver but couldn't work it out either.

Much as I hated to do it, I finally used iTunes on my computer to transfer the ring tones to my phone. I don't like the iTunes interface since it is very cluttered and non-intutitive, especially when using a screen reader, but at least I could transfer the ring tones that way.

The trick to transferring ring tones using iTunes is to:
- Create an M4A file (using a free program such as Audacity).
- Change the extension from M4A to M4R
- Use ITunes to transfer the M4R file.

I don't know why Apple makes this so difficult. Something that should be trivial to do turns out to be fairly complex in the Apple world. Wouldn't it be nice some day if we could actually browse our Apple file systems and put files wherever we want just like on real computers? Well, maybe that is the price one pays for having a closed and (hopefully) more secure system.

--Pete