SAMR model--Substitution, Augmentation, Modification, Redefinition to introduce technology into learning processes by Christopher Pappas, March 3, 2016
Catherine Davis outlines 5 simple things to do when designing e-learning for adults with low level literacy skills or for non English speaking adult (ESL) populations. Basically it is: simple interface without bells and whistles; simple short sentences; lots of visuals (infographs) and photos; on-screen text and visuals that support audio - audio is the driver of the pages; provide supplemental full audio transcript
Create activities that encourage adult learners to use sites like LinkedIn and Google Plus as invaluable tools. This can help them to not only build their social network, but collaborate with those who share the same interests.
However, mature learners prefer to engage in eLearning experiences that help them to solve problems they encounter on a regular basis (in the here-and-now, rather than the future).
Motivation is key with adult learners. As such, you will need to motivate them to learn by offering them a reason for every eLearning activity, assessment, or eLearning module they'll need to complete.