In terms of sound quality there will be no difference between using bare wire, pins, spade lugs (the connector you bought), or banana plugs. Spades and banana plugs are just a lot more convenient if you have to connect and disconnect the speakers.
If you bought enough of the spades for your speakers, I'd just use them but you'll have to verify that you can actually get them on your receiver's binding posts. A lot of receivers that have '5 way binding posts' don't actually accept spades because they have a little collar on the bottom.
Locking bananas are nice but you could get by with regular bananas unless you have some reason to fear that they will become disconnected easily (like if you have a child that would pull on the speaker wires.

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