get RPM from Illumina website (no restrictions apparently).

https://s3.amazonaws.com/webdata.illumina.com/downloads/software/bcl-convert/bcl-convert-4.2.7-2.el7.x86_64.rpm


bcl-convert wants to be able to write to /var/logs/bcl-convert, so you must bind a user writable directory 

    mkdir logs
    singularity exec --bind logs:/var/log/bcl-convert bcl-convert.sif bcl-convert --help

or

    singularity exec -wf bcl-convert.sif bcl-convert --help

