You seem to have posted this twice…

Presumably you are seeing nothing on the meters when you feed it with ADAT. This may be because the clock is not set up for ADAT (SETUP/clock/source). You are wise to use the routing presets, cos doing it manually is not for the beginner. BUT, the routing presets do not change the sync source (sample clock), so this may be your problem. Once "Source" is set to "ADAT" make sure that 2 lines below ADAT is shown as OK (meaning locked).

You could usefully test the rest of your setup by going MIC -> MR816 -> ADAT ->MR816->Cubase. If this does not work, your problem is not the H8000 ….