Thanks for your help, I am now trying to run both HUMAn 4 and MetaPhlAn 4 I installed both software in the same environment and maybe that made it difficult to setup the databases (I got an error similar to Humann database errors (a short novel) - #3 by RbccBstn). I am currently re-downloading the metaphlan database to make it work but I wanted to thank you for this reply above.
Best
Andrès