Why doesn't my ringtone show up on my iPhone?

It has to be under 40 seconds, and in M4R format if you copy it from a computer. MeloCut takes care of both.

Can I set a text tone too?

Yes. On iPhone choose Text Tone in Sounds & Haptics. On Android choose Notification sound.

🔔 No ringtone yet? Making one takes about 30 seconds.

In the Ringtone Maker choose MP3 (or M4A) and download your ringtone. It goes to the Files app, in Downloads.
Install GarageBand (free, made by Apple) and open it. Start any instrument, for example Audio Recorder.
Tap the tracks view button, then the loop icon in the top right → Files → Browse items from the Files app, and pick your ringtone.
Drag it onto the track, then tap the ⌄ arrow in the top left → My Songs.
Long-press the song → Share → Ringtone → Export → Use sound as… Standard Ringtone.

Choose M4R (iPhone ringtone) in the Ringtone Maker and download it on your computer.
Connect your iPhone with a cable. Open Finder on a Mac, or iTunes or Apple Devices on Windows, and select your iPhone.
Drag the .m4r file onto your iPhone in the sidebar. It copies over in a few seconds.
On the iPhone open Settings → Sounds & Haptics → Ringtone and pick it.

Choose MP3 in the Ringtone Maker and download it.
Open Settings → Sound & vibration → Phone ringtone.
Tap +, Add ringtone or My sounds (the name depends on your phone) and pick the file from Downloads.
For one contact only: open the contact → ⋮ → Set ringtone.

Keep it between 20 and 30 seconds, start just before the chorus and leave the fades on. If it's too quiet, raise Volume in Effects.