Hello Jiman,
yes, I already checked the post you shared, but unfortunately I can't find where the process is breaking.
The error log points at folder
/home/jasper/jasperreports-server-cp-8.1.1/
for missing permissions, but I can't understand why, since that whole folder has jasper:jasper and the user can access it freely.
Do you know what the issue may be?
I tried installing the product on a series of other VMs, even other OS like Ubuntu, but I get the same exact error when not using a non-root user.
Best regards,
Leonardo