Cannot set a purchased ringtone song as my ringtone

I purchased a ringtone song through the Tone Store but am unable to set it as my ringtone (for all calls). I've clicked the option to download but its not showing as an option to choose within the list of ringtones. When I go to the ringtone store it shows it as a purchased item but there is no option to set it as my ringtone, it only lets me play the song. There is a note saying the song was in fact downloaded. Clicking "more..." at the bottom right of the screen just brings me back to the menu option for choosing tones, purchased, etc., it doesn't provide an option for choosing the song as my ringtone (its basically a back button).

I saw 3 other exact same questions on this forum and have reviewed the answers. Each answer simply gives a link to the same apple support instructions which I've just summarized above.

Does anyone have any advice for solving this problem?