only this message appears, but I'm really not sure what to do after
Well, it clearly say that both the geometry, default morphs and textures are missing for that particular hair style.
So either you deleted the files by error, not installed the asset correctly, or the asset itself is broken.
Because, yes, broken assets happen, Daz Studio installation process totally discard the error that happen during the installation (especially the ones due to the archive), and some archives are corrupted, having some files that can't be uncompressed, and therefore can't be installed.
Try to manually install the asset by opening the archive(s) (there's possibly more than one) and uncompressing them in the main directory used by Daz Studio (where there's the data, People, presets, Runtime and other directories). While doing this, ensure that the files listed in the error message are effectively present in the archive, and have effectively been correctly installed.