My Garmin Drive 50LM is bewildering me, can YOU help???

Firstly, can I say a BIG BIG thank you to the knowledgeable and clever people who I’ve been able to get some information from over the past few months!

I’ve managed to get my Edge820 and Etrex 20x working brilliantly with some map data. However, I am a bit stumped with my latest purchase, a brand new Garmin Drive 50LM automotive sat-nav. I’ve searched the forum but whilst I can find a lot of info about the Nuvi series, not much about this newer device (which I think is a new name for the Nuvi line)

I’ve downloaded the gmapsupp content for both Europe and also the GB OS Discoverer products. These work on my etrex device, but when I put them in the ‘Garmin’ folder on the Drive 50's SD card and boot up I get an error message saying the maps cannot be unlocked. I’ve searched the site and I THINK that this means I need to patch the Drive 50, but I’m not 100% certain.

I’m using unlocked maps in each occasion…can anyone advise on my best way to proceed to get the gmapsupp files working please - do I need to try and get them into the ‘.system’ folder (i’m not sure I have enough room for them, hence the SD card approach)

Any and all advice very much appreciated, thanks all - and IF i've missed an obvious post in my search, apologies!
J