The adult learning ecology has expanded to include digital access, requiring enhancement of theories in the specific context of low-literate learners who may not have previously benefited from educational technology. The Digital Learning Ecology (DLE) framework identifies the three dimensions of context, design, and motivation, considering theories of cognitive learning, multimedia design, and language learning ecology that help support low-literate adults. A mobile learning solution based on DLE, designed for the Barbara Bush Foundation XPRIZE Adult Literacy competition, is described. The app design utilizes context proximal to adult learners' lives to motivate and maintain active engagement, improve multiple literacies, foster engagement, and encourage persistence. DLE dimensions are mapped to specific features of the app, along with the underlying cognitive principles that support learning. Both internal evaluations by authors and external evaluations by XPRIZE demonstrate significant improvement in learning outcomes for low-literate adults. Further, many low-literate adults in this study demonstrated low digital literacy, indicating a design need for a more accessible user interface with enhanced signifiers compared to those provided by universal design principles. Carefully designed mobile solutions based on the DLE framework can enhance and expand the learning ecology for low-literate adults, supporting both formal and non-formal learning environments.