Hello, @dbeltran, @bdepaula, and @isimomun:
I ran into a similar problem as Miguel Andrés, where the structure of the scratch folder in Fugaku does not follow root+account+user. I have an extra folder in between root and account, data. So Autosubmit 3.15 was failing due to the folder not existing.
I saw !296 (merged) and #912 (closed), so I applied Miguel Andrés' commit and made the necessary changes for 3.15.
Even though now it is working in Fugaku, I am not entirely sure if the changes have not broken for all the other platforms. So that would have to be checked before being merged to the 3.15 branch.