Just got a Play. Put my sounds on the SD, but the Play doesn't see em

Bit late to the party getting a Play, but never needed a groovebox until now as I primarily use FL, Bitwig and Project One. Got sick of being attached to a PC and needed to unplug and be a bit more portable.

Anyway…I have a huge collection of one-shots from battery, maschine, spark, sample packs from wave alchemy etc…and wanted to get a lot of my own drum sounds onto that SD card. Tried it, but after re-inserting the sd card, the files I copy / pasted, aren’t seen.

As far as I’m aware, I followed the correct format by making separate folders for kick, hats, snare, percussion ( which contain only wav files ) and then put them in a folder with my name, and copy pasted that folder into the folder with all the other “Artists” folders.
Navigating via the Play screen, I don’t see artist folders, or my own folder among them.

Could someone please advise me about what I’m doing wrong, and how to fix it so I can see and access the files I put on the SD card ?

Thanks