How to get own Ringtones on to a Oneplus Nord

[Netherfield]

Just bought a Oneplus Nord, can't find out how to get personal ringtones on to it.

Plugged in to computer USB, only five files appear

adb_config_Linux_OSX.sh
Android filetransfer(OSX).dmg
Autorun.inf
Oneplus_setup.exe
Oneplus_USB_drivers_setup.exe

No sign of ringtones or music folders

Using Oneplus switch, I've got the ringtones in Dropbox, but can't find a way to get them in to the ringtones folder.

Daughter has a Oneplus phone, although a different model where she's had no problem.

 

[B. Diddy]

This is an old article, but the basic principle should still be the same: Android 101: Adding your own custom sounds to Android events | Android Central

When you connect the phone to the computer, swipe down the notification panel, tap the USB notification, and make sure MTP (or File Transfer) is selected. Then explore the phone in Windows Explorer.