Thanks for your reply! I solved this!
If I passed only the fastq like this I got error of the database match.
humann -i SRR88998813.fastq -o ./OUTIE/SRR88998813 --threads 20
After this I tried to use v296 but I got the errors I mentioned before but I finally solved locally rebuilding with diamond as per suggested here and pointing every database to use the v30 one (instead of the 296 that was set up at the cluster).