a question that recently occurred to me: I've heard that one of the reasons for operation barbarossa was because of a lack of resources especially oil. Why weren't the nazis able to get oil and other resources from the countries they had already subjugated? Especially France which was very much a first world nation
You can't obtain something from the place when given resource is absent. In 1940 oil production was nowhere near as common as today, and there were few places Germans could have received the crude oil and petroleum products from. According to the League of Nations reports for the 1940, the top producer of the crude oil (including shale oil) were United States (182.6 MT), followed by USSR (29.7 MT), Venezuela (27.4 MT), Iran (10.2 MT), Indonesia (7.9 MT), Mexico (6.7 MT) and Romania (5.7 MT). Germany and the countries that were either allied, conquered or subjugated, save for Romania, had negligible oil production, at least in comparison to USSR. Germany iself produced 0.6 MT of oil and could count on production in Poland (0.5 MT), Hungary (0.14 MT) and Romania (5.7 MT). Other countries enjoyed negligible local production: Italy - 0.012 MT, Austria - 0.1 MT, Czechoslovakia - 0.02 MT, France - 0.07 MT). The only place where Germans were able to get substantial amounts of oil was Venezuela, but even if it was possible due to significant Royal Navy presence in Atlantic that effectively blockaded supply lines to Germany, sentiments of Venezuelan citizens were generally anti-German at the time, so chance of the country joining Axis were minimal. Although Venezuela supplied Italy and Japan after declaring neutrality, it severed diplomatic relations with Axis Powers on 31st December 1941.
Germany had a lot of coal (186 MT compared with 132 MT or USSR and 230 MT of UK) and could receive iron ore from France (10 MT) or neutral Sweden (8.3 MT) that could bolster domestic production of 3.1 MT, but their steel production was already substantial (23.2 MT), especially when compared with that of USSR (19.1 MT) and United Kingdom (11 MT). Same could have been told of aluminium, as Germany was the top world producer of this material in 1940 with 0.24 MT (30% of world production). But the only reliable source of petroleum was either USSR with its oil fields in Caucasus or the Iranian fields controlled by the British.
P.S. All amounts expressed in annual production in millions of tons (MT).