Hello,
The commission allocation feature is available for the premium version of Crowdfunding plugin.
If you’re using the premium version, you are given access to certain add-ons like ‘wallet’ which will allow you set the commission allocation.
After enabling the ‘wallet’ add-on, go to crowdfunding > settings > wallet (tab). From there you can set the commission allocations etc.
Here is a link of the documentation which you might find helpful: https://docs.themeum.com/wp-crowdfunding/money-management-explained/