I want to level up my wizard from level 1 to 2 using the website d&d beyond. I select level 2 and apply. Then it gives me the option to CHOOSE ARCANE TRADITION. there is a drop down menu but when I click it, it only gives me the option for evocation, which doesn’t appeal to me. What do I need to do to get the other options?

Buy them.

The Evoker is the only free Arcane Tradition, the rest must be purchased from this website.

Fair enough but it just says “buy them” but not how to do so. I bought the Players Handbook and that worked. They should spell it out more clearly for people who are new. 

Quote from dbrundin >>

Fair enough but it just says “buy them” but not how to do so. I bought the Players Handbook and that worked. They should spell it out more clearly for people who are new. 

  If you bought the PHB I thought all the PHB options would be there.  I'd put in a ticket if that's the case.

If you click on it it it should automatically redirect you to the marketplace.

It does redirect to the marketplace in general but it’s not clear what you need to buy there to unlock those things 

Quote from dbrundin >>

It does redirect to the marketplace in general but it’s not clear what you need to buy there to unlock those things 

 
In the Marketplace click on the titles. It tells you what it unlocks. It also gives you options to buy things individually if you're more interested in the specific subclass, race or item, etc.

I wish there was a code or something on the physical books that we could enter on our accounts to access the same content. I own hard copies of the sourcebooks and everything, but there's no way (that I can find) to add them to my account. Could I upload a picture of the barcode or something? Idk I don't think they have that feature but if they do and someone else has figured it out, please let me know!

Is it possible to use the artificer school? I have attempted to purchase from a lot of available sources and it does not seem any on dnd beyond will allow me to add this.

There is no artificer school for wizard. Artificer is its own class. You can acquire from purchasing the whole book that features it or by purchasing any Artificer subclass specifically, which will also unlock the full class.

I also do this. i am dming a campaign for a kenku rogue/cleric of life, a tabaxi rogue soulknife/war mage wizard, and a barbarian path of the totem warrior and have shamelessly hombrewed the non-public free options

I am having the same problem. I think I have all the sourcebooks through being in my DM’s campaign. Those traditions are clearly in the PHB, so if I have that why wouldn’t I also have three option to choose them. It’s very frustrating.

 Would I need to purchase the PHB myself? I’d be ok with this, but only if it’s necessary and if I know that’s what I need.

1. Is your character actually in that campaign?
2. Is Content Sharing actually enabled for that campaign?

If the answer to both those questions is “yes,” then you and your DM should both follow this link and make sure your Account Entitlements are in sync: (https://www.dndbeyond.com/account/marketplace).

^^ IamSposta covered it best.  Likely, content sharing is not turned on for that campaign.

Thank you, your answer helped me figure out what was going on. The character actually was removed from my DM’s campaign. Which is fine because that DM quit the shop where I play and I have been playing in another DM’s campaign anyway. Since she quit it’s only a matter of time before I lose access for my other characters. 
So your answer helped me realize that I would be able to unlock the traditions by purchasing the PHB for myself. Which I did and it worked.

 Thanks again!