why does this have to be conditional?
"I should" always translates to conditional = "měl bych"
I just completed the previous exercise and “Měl” is used without “Bych” as “supposed to”. I thought “Měl bych” meant “I would like....”. Which one is it?
That is consistent with the usage here, isn't it?
Mám koupit. I am supposed to buy.
Měl bych koupit. I should buy.
Hard to comment on the "would like" without seeing the actual sentence you got.
I finished the module today. I finally realized I should have been saying, ,,Rád bych koupil..”all along.
Yes, that is possible and not incorrect, though most often we just say "Chtěl bych...." or less often "Rád bych ..." or "Chtěl bych koupit ..." when actually in a shop.