Welcome!
Some information on the meaning of lexiles:
https://lexile.com/about-lexile/grade-equivalent/grade-equivalent-chart/Note that there are no official grade equivalents for lexiles. These two charts (or three, if you count the second one as two) describe normative performance, not grade-level standards or expectations. IOW, the first chart tells you where the middle 50% of students in each grade level score on the lexile system in standardization studies. The second chart tells you where a selection of supposedly grade-level text scored in text complexity studies based on the lexile system. The range in student populations is noticeably lower than the range of what is considered grade-level text.
Either way, her lexile suggests that she is comprehending at a high school level--though one should keep in mind that, as much as the STAR is an adaptive test, with a grade one start point, her score is probably not as reliable as a score nearer the grade-level mean would be, so probably no need to search for adult reading level selections for her.
(Obviously, one can still conclude that she is an exceptionally strong reader!)
