According to these lines you should set max_fsm_pages to at the very
least 5306160
You have a humongous amount of RAM, you could set it to 10000000
> INFO: free space map: 79 relations, 1948399 pages stored; 5306160 total
> pages needed
> DETAIL: Allocated FSM size: 500 relations + 2000000 pages = 11769 kB
> shared memory.