In the 6.1 it
should update itself over the 4G/LTE connection. AFAIK that's not the paid data you can add, but the data that is part of the WeConnect subscription. If you enable the setting it should also prioritise updates in the areas you regularly drive in.
If you want to do it manually there is a procedure to download the map update to a USB stick. You'll need a USBC one or an adapter and use the dash USBC (the rear ones are power only) we got this double ended one
https://www.amazon.co.uk/gp/aw/d/B07YYJRXQR
VW Link to updates:
www.volkswagen.co.uk
I haven't done it yet myself as our Caravelle is still new enough to be in the inclusive WeConnect period and everytime I tried and checked the downloaded update on the USB stick was no newer.