So I'm not a programmer
I have some bad news for you, you're a beginner programmer and sysadmin now.
∧＿∧ ∧＿∧ ∧＿∧ ∧＿∧ ∧＿∧
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（ つ┳∪━━∪━∪━━∪━∪━∪━┳⊂ つ
｜ ｜ | ┃ !!!!!YOU GAIN EXP!!!! ┃ ｜ ｜ ｜
（_＿）＿） ┻━━━━━━━━━━━━━━┻ （_＿）＿）No refunds.
I would guess /opt/bbs/opt/schemebbs/data has permissions the newer docker doesn't like. File an issue here if you're fine with using github https://github.com/TeamWau/docker-schemebbs/issues high chance you won't get a reply.
Permissions means things beyond basic directory access controls, I didn't like playing with docker years ago so I don't know with it.