注・かなり昔に描いてるのでクオリティは低いです。

・。

Note: This was drawn quite a while ago, so the quality is low.

Literal

Note: considerably past [at-に] drawn so quality [topic-は] low [copula-です].

注 ('note') opens a disclaimer. かなり昔に ('quite a while ago') sets the temporal context. 描いてる is the casual contraction of 描いている. クオリティは低い uses the English loan クオリティ ('quality'). A self-deprecating artist's note — common on Japanese art-sharing sites where people post old work.