tankerkiller125 yeah, you're right. With my table prefix that's exactly one letter too much.
I will remove the prefix for now.
EDIT: Found that's already known error:
FriendsOfFlarum/taxonomies2
EDIT #2: That's solved with prefix removal, but this is a new error:
Can't create tablemzzewjrmhd.fof_discussion_taxonomy_term(errno: 150 "Foreign key constraint is incorrectly formed")
Reported here: FriendsOfFlarum/taxonomies3