This study identifies a key distinction between digital and traditional supply chain finance (SCF): technology-empowered financial service providers (FSPs) are no longer completely uninformed parties in financing markets. By examining an underexplored digital SCF scenario involving upstream focal firms and financially constrained downstream dealers, we reveal the effective signals that enable downstream small and micro enterprises (SMEs) to access SCF, and explore how and when FSPs use different screens to refine financing decisions. Using a dataset from MYBank, a leading Chinese big tech lender with nationwide coverage and a dominant market share in digital SCF, we find that a dealer's procurement amount from focal firms is a strong signal, particularly when credit limits are higher. Meanwhile, FSPs utilize stakeholder cues and digital footprints within their ecosystems to refine financing decisions. Three key stakeholder groups—owners, focal firms, and peer dealers—and regional digital financial inclusion influence the effectiveness of procurement signals. The impact of distinct signaling-screening mechanisms varies across firm size, platform registration duration, and regional marketization. Robustness tests, including IV-2SLS regressions, the Heckman two-step method, stringent fixed effects and subsample analysis, validate our findings. The study enriches the SCF literature by revealing the role of supply chain data in credit creation and identifying various signaling-screening mechanisms. It also extends screening theory by illustrating the contingent nature of screens. The findings respond to China's recent policy initiatives on decentralized supply chain loans and provide guidance for SCF practitioners.