The Supre Drive is designed to be compatible with Shimano 12-speed HG+ chains.
The Supre Drive uses a slightly longer chain than a standard, non idler pulley drivetrain—typically only 10 to 20 links longer than a standard 126 link chain.
Route the chain as illustrated.
Ensure the narrow/wide links in the chain match the narrow/wide teeth on the derailleur pulley since the derailleur chain guide does not allow enough space for the chain to re-orientate itself on the pulley once installed.
While in the highest gear, hold both ends of the chain and release or pull the chain so that there is roughly 10mm between the chain that's over the tensioner pulley and the section of chain between the idler pulley and the chainring.
The goal should be to have the chain as long as possible while keeping the measured gap larger than 10mm.
Mark where the chain overlaps and cut the chain one link shorter than at the mark (in other words, cut the chain in consideration of the added length of the quick-link).
Connect the ends of the chain with a quick-link.
The chain length can be double checked with the quick-link loosely connected, so that you can easily undo it if the chain length needs adjustment.