Hello, I'm Quinn and here to help!
In case you might have missed it, on the Minecraft Launcher make sure you’ve selected “Minecraft: Java Edition” on the left side
If it still says “Buy Now,” the most common reason is that you’re signed into the wrong Microsoft account. Please sign out of the launcher, then sign back in using the exact Microsoft account you used to purchase Minecraft.
- Go to https://account.microsoft.com/ , sign in with the account you've used to buy
- On the left, click Order history
- Check if you see “Minecraft: Java & Bedrock Edition for PC” or “Minecraft: Java Edition”