Slurm currently fails to build because it fails to build some plugins (ofed, pmix_v6).
These work for me locally with dependencies on libmad-dev, ibverbs-providers, libumad-dev and libpmix-dev=6.1.1 (experimental)
installed.

I am testing whether it is safe to move to pmix v6; it is currently in experimental.

Regards
Alastair