Just to be clear, a 5G phone generally describes the cellular connection. That’s not the same as whether its hotspot is in the 2.4g or 5g wifi range.
If your phone is Android, you can control whether the hotspot is 2.4g or 5g (in Android 12 and 13 it is kind of obfuscated as “extend compatibility”, meaning 2.4g. If you set your phone’s hotspot to 2.4g, the Mango should be able to connect/repeat it.