So I want to build a Feat in D&D Beyond similar to Fey/Shadow Touched. 

I want the player to choose which ability Score (Charisma, Intelligence or Wisdom) they want. This will increase the score by 1.

Then I want them to be able to pick a 1st level spell from the Abjuration or Transmutation schools of magic. And that spell would use the ability Score the player choose in the first option.

When I try to build this using options, you can only add Actions, nothing more. 

How do I build something like this with this system?

You would have to create it as 3 feats, one for each ability score.

Really? There's no options at all to have it done in one feat?

Really 

And how about making a list of spells that the player chooses 1 from? Options doesn't allow for spells either. 

See the Subclasses & Species FAQ #15, feats work the same way: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq).