Can I play Fortnite on a PC that does not meet the minimum requirements?

See above

Yes, but it's not fun.

Rarely it doesn't work, mostly it does, but it's probably going pretty badly.

Fortnite is fun?

If it is really too weak, you will be advised that you are below the minimum requirements, but even if you are above this requirement, it will hardly work, because you have to stick to the recommended ones

Perhaps.

But you don't want it (even if you might think so).