The installation guide for AL wiring is in the first post of this thread, faithfully follow the diagram - at the end of the guide -.
E.g:
The red/black 10-pin coupling is an ISO connector, you can buy it in many well-known places (googling, etc).
Also here:
www.tme.eu (search in 4CARMEDIA), see applications, contact terminals, etc. on that same website.
The other connectors and relay support/carrier are original VW.
Buy from VW dealers or VW stores near where you live, they are also offered on well-known websites (googling, etc).
Help link:
ETKA online and more.