I'm afraid you can't. Even if you buy Explaindio PRO Creator Pack without the Standard Version, you will not be able to use Explaindio without Buying the Explaindio License.
Here is why:
1. Explaindio is the Standard Version which is the main product that comes as an Explaindio Video Creator Monthly or Explaindio Video Creator Annual or an Explaindio Video Creator Special One-Off payment subscription.
2. Explaindio PRO Creator Pack is an Upgrade or Upsell which gives you 200 3D Intro, Outro's, and Deluxe Sting Animations and 700 Premium Transitions for your Explaindio software.
3. Since Explaindio PRO Creator Pack is not independent, you will need to subscribe for the main product Explaindio Video Creator Monthly or Explaindio Video Creator Annual or an Explaindio Video Creator Special One-Off payment subscription. Else you can't use Explaindio with only Explaindio PRO Creator Pack in your account.