Technology is technology, it's about exploiting the laws of nature to do things.
If you want to create refined metals you'll need to heat it, you'll need a source of heat, and you'll need to isolate it from the surrounding water long enough to finish the process.
Being underwater makes a lot things much much more difficult or impossible.
That's even ignoring your species won't be incidentally exposed to sources of easy energy like fire occurring naturally before learning to create it yourself.
There's certainly workarounds and alternatives that could make it _possible_ to develop technologies like fire, metallurgy, complex chemistry, etc. but they'll all be so much harder to discover and do that no early civilisation would consider the required experimentation worthwhile.
Again, you're thinking human centric. Maybe they could do amazing things with non metallic materials which we haven't needed or which haven't been practical for us due to the different circumstances.
there are some pretty cool scifi books that look at how an aquatic species might develop technology. the "ringworld's children" involves a species that develops on a frozen world with an ocean beneath the ice.
Ganymede's oceans might be the largest in the entire Solar System.
1. https://en.wikipedia.org/wiki/Ganymede_(moon)#Subsurface_oce...
2. https://en.wikipedia.org/wiki/Callisto_(moon)#Internal_struc...