How to create a ringtone with part of song using a GarageBand?

Not sure what forum this goes under but I need help creating a ringtone.

I want to use part of the song "Frankenstein" by Edgar Winter Band as my ringtone.

It was very easy to do on a droid 10 yrs ago, just needed the song to be on the phone.

Now I have an iphone 15plus and need to create the ringtone first, using garage band.

It's not working for me. I bought the song, installed garage band, etc. No luck.

Is there an easy way to create a ringtone from a song?

TYIA for any help.

[Re-Titled by Moderator]