I bought red dead 2 story mode and online but it only allows me to play story mode and...

Are you sure that you purchased the full Red Dead Redemption 2 and not just the Red Dead Redemption 2: Story Mode. If you purchased the Story Mode, then you need to own Red Dead Online in order to play it. Story Mode is just DLC for Red Dead Online and cannot be played or installed without Red Dead Online.

So if i purchase red dead online,will i immediatly be able to play story mode,i wont need xbox live so that i can play red dead 2 story mode will I?

I purchased red dead 2 story mode but i cant seem to install it, so all i need is internet connection and to purchase online mode and it will immediatly work?

Yes, I have Red Dead Online which allows me to access the story mode, without it it is not possible to play.

Check your account: https://account.microsoft.com/billing/orders, and confirm that it really is the RRD2 version that has the Online version and story mode. I'm thinking that it only has the story mode, that's why it's not being able to play.

Did you purchase Red Dead Redemtion 2: Story Mode, or did you purchase Red Dead Redemption 2 the full game?

Story Mode is just an add-on for Red Dead Online. If you had access to Game Pass games you could download RDO and then purchase Story Mode to play the single player. RDO has been removed from Game Pass. If you only purchase Story Mode, you will now need to purchase RDO to keep playing the single player.

So to wrap it up, to play the single player portion you need to have purchased either the full Red Dead Rredemption 2 game or you have to have purchased BOTH Red Dead Online and it's Red Dead Redemption 2: Story Mode add-on.

Story Mode is merely an add-on for RDO. It is not the full single player game.

Did you actually purchase the full game or have you purchased Red Dead Redemption 2: Story Mode? Story Mode is just DLC for Red Dead Online and is only playable through the Red Dead Online game itself.