If you want to skip the check, press and hold ESC key while loading. If you open a project file that doesn't have the required samples or presets, FL Studio performs a search in the folder where the loop file was loaded from, then its sample folder, and all custom folders that are added to the Browser (see Browser File Settings). It retains all data that belongs to your project, but note this does not include any samples used in the project.
FL Studio Project File (*.flp) - This is the default native project format of FL Studio.