Just to show when things won't work via a regular file manager.
Like in my AntiX linux install which uses spacefm and rox file manager.
With no automount given like in Ubuntu or MX linux with XFCE.
But using a Window Manager instead like Icewm. I installed Airdroid on my phone.
Signed up after the application install so I could log in.
My phone is turned on.
No developer settings touched. I open the Airdroid app on my phone.
Then I go to http://web.airdroid.com/
I log in. I open my music folder in my phone in Airdroid shown in the screenshot below
Then I open rox file manager in Antix and open my Music folder. I drag and drop a music mp3 file from rox file manager to my browser window music file on my phone that is shown open. It loads the mp3 on the phone. Airdroid screeny below.
This is on a bare window manager install with no special bells or whistles to need mountup. Everything is handled through the airdroid app and firefox in my Antix laptop.
Just showing more ways to skin a cat.
Edit: I borrowed the idea and thanked LennyUsesManjero for
You can also try using web based managers like Airdroid. It uses the web browser as a file manager to connect with your device and do file transfers and more