What happens if I don’t have enough space for the remaining resources from the season pass?

I suggest you make armies that are almost 100% made of dark elixir troops.

You can also upgrade your hero.

As well as upgrading your dark elixir storage.

Continue doing so until you have enough space for your dark elixir.

Good luck!

It will fill the empty storage, and any remaining that you earn will fill it again as space frees up. After that, you can't collect more Dark Elixir from the Drills.

If you aren't sure about how to spend the dark elixir, just rush your TH to Level 9 where you need a lot of dark elixirs to upgrade your heroes alone.