API Platform Admin 4.0 has the same API as API Platform admin 3.4, but now requires react-admin v5.
If your application only uses components from the '@api-platform/admin' package, it should work out of the box with API Platform Admin 4.0.
If you have done some customization based on the 'react-admin' package, you will probably have to make some changes. Read the UPGRADE guide from react-admin for further details.