Is there a way to auto autoupdate CRL files automatically ?

Unfortunately, CRL support is pretty minimalist. F5's answer was to me "OCSP should be used preferably".

You could write a bash script to download the CRLs (and concatenate them if necessary) and use cron to execute it regularly.

I used icall.

From this thread, it worked great. https://devcentral.f5.com/questions/sharing-icall-for-crl-update