the overcurrent protection is likely on the output, not necessarily on input
i would think that since they expect about 45A inrush, (if turn on happens
to be at maximum voltage and input capacitors are fully discharged),
that it can handle that inrush reliably long term
so its likely your 3A fuse will do
it isn't clear is you need a specific form factor for the fuse
a search at digikey yielded 77 littlefuse varieties with 4A or 5A and 250 or 300 VAC ratings
maybe one of those will help
i did not look for trip current vs time