This appears to only be in German: https://zwwa.de/

But this site has a few different languages, selectable in the upper-right corner of the page: https://mihr.com/

Note that the bulk of the teachings are about self-evolution via transmuting our vices into their corresponding virtues. It is that transformation that unlocks our ability to consciously travel during sleep.

The key to all such teachings is that becoming consumed by compassion is the real goal; all else is just added benefit.

As Steel Pulse put it so eloquently so long ago, "Love is the golden chord that binds all commandments." It is also the scaffolding that boosts our abilities to their greatest height; but, in reality, the spiritual path is really about stripping away our selfish ego-nature that impedes our realizing our full potential.

Peace be with you.