so ye, i can't find anything about that in the config, and when i excavate without auto-pickup, there's items basically everywhere.
And the gifs from the diggus maximus page are showing grouped items without auto-pickup, so are these from an other mod ?
otherwise how can i enable that

by 'grouped', i mean all the mined blocks are at the same place, like with ftb ultimine

When excavating without auto-pickup, diggus just simulates the player breaking all the blocks individually. When the block gets broken, it's drops just fall to the floor where it was. Auto pickup just automatically picks up the items off the floor and sends them to your inventory. It wouldn't be difficult to add an option to move all drops to the location of the broken block.

And actually looking at the gifs now, if you watch the players inventory all of the items besides one do get auto picked up. This was a really old bug in the mod where the initially broken block was excluded from auto pick up. It was quickly fixed, but I forgot to change the gifs.