Methodological is the adjective for methodology: it is about the methods and principles you use when you study a subject or do a piece of research. A methodological problem is a problem in how the study was set up, not a problem in the topic itself. A methodological choice is a choice about tools, samples, steps, and rules of evidence. This is university and professional language. You will see it in papers, reports, and lectures, almost never in casual talk. Though actually, learners often meet methodical first and then treat methodological as a longer, fancier twin. It is not. Methodical means “careful and in order” in daily work; methodological means “about the system of methods.”