illiterate
adj.adj. unable to read or write. You can also use it to describe someone who does not know much about a specific subject, like computers.
adj. unable to read or write; lacking basic literacy. Often used to describe a lack of proficiency in a specific field, such as digital or financial systems.
The charity helps illiterate adults learn to read.
Despite being a brilliant mechanic, he remained functionally illiterate and struggled with the written safety manuals.
In an increasingly digital economy, those who are technologically illiterate face significant barriers to employment and social participation.
First attested in 1425–1475, in Middle English; from Middle English illiterat(e) (“uneducated, ignorant of Latin”), borrowed from Latin illīterātus, illitterātus (“unlearned, ignorant”), itself from in- (“un-”) + līterātus, litterātus (“furnished with letters”) (see -ate (adjective-forming suffix)), from lītera, littera (“letter, character”). The noun was derived from the adjective by substantivization, see -ate (noun-forming suffix).
Often used with a qualifying adverb like 'functionally' or 'digitally'.