Hello krumiel,
Novation list version 2.7 on their downloads page as the driver for their Launchpad Mk1 for the Mac (under 'discontinued products'):
https://global.novationmusic.com/support/product-downloads?product=Launchpad+MK1
Hence I would imagine that you would need to install that version specifically, then reboot, making sure that the Launchpad is attached and powered up *before* you launch Hauptwerk.
I don't know whether that driver version is fully compatible with current macOS versions (given that Novation no longer officially support the Mk1 Launchpad).
N.B. also: Hauptwerk queries the list of audio and MIDI devices from the operating system when Hauptwerk launches, and it expects them to remain connected; it doesn't support 'hot-plugging' devices. If you've told macOS to launch Hauptwerk automatically upon login then you might need to try setting the 'Minimum time to wait on start-up' setting to (say) 15 seconds on Hauptwerk's 'General settings | General preferences | Advanced ...' screen tab, so that there is some extra time for the operating system to finish starting all of the drivers as it boots, before Hauptwerk launches properly and queries the list of devices from the operating system.