How to link Steam Bought Settle - Carlisle to TANE

Just bought Settle - Carlisle on steam and having issues linking it so I can use the Settle - Carlisle route in TANE

Thanks

Did you buy TANE on Steam?
If not, the game is likely not bought using the same account so not linked. In that case I would suggest returning it and buying it where you got TANE.

No, I bought TANE of the Auran website, I would have bought it on there but the money was locked on my steam account since it was a steam voucher used to purchase it

You need the Steam version of TANE to buy and use any DLC for TANE on Steam.

If you don't own the Steam Version, then that DLC is not going to load into the Auran one as they're authorised differently.
I would try to return the DLC back to Steam and buy the Auran version; or re-buy TANE Steam version when its on sale.