You can manually update by copying the contents of http://wilson.bronger.org/lensfun-db/version_1.tar.bz2 (the latest stable file list)
in to ...\Program Files\Affinity\Affinity Photo\Resources\Lens Profiles on windows though I would recommend you take a backup of the current contents first just in case something goes wrong.
This is on windows only.
I think though the lensfun project is stalled through lack of resources - it's a shame really as a lot of commercial software is relying up on it but having spoken to some of the volunteers (it's all volunteers) none of the commercial programs that rely on have donated either money or even some staff hours to help with the profiling.