The Gemara in SANHEDRIN 59b says:
אמר רב יהודה אמר רב אדם הראשון לא הותר לו בשר לאכילה דכתיב (בראשית א, כט) לכם יהיה לאכלה ולכל חית הארץ ולא חית הארץ לכם
§ Rav Yehuda says that Rav says: Meat was not permitted to Adam, the first man, for consumption, as it is written: “And God said: Behold, I have given you every herb that brings forth seed,... for you it shall be for food, and for every animal of the earth...(Genesis 1:29–30). It is derived God told Adam: Eating vegetation is permitted to people and animals, but eating the animals of the earth is not permitted to you.
Tosafot says that Adam HaRishon was able to eat meat that had died by itself he just was not able to kill the meat and eat it.
Others disagree. SEE HERE
According to the opinion that Adam was allowed to eat meat of an animal which he did not kill how do we understand the following Gemara.
The gemara (just after the one cited above) says: מיתיבי היה ר' יהודה בן תימא אומר אדם הראשון מיסב בגן עדן היה והיו מלאכי השרת צולין לו בשר ומסננין לו יין הציץ בו נחש וראה בכבודו ונתקנא בו התם בבשר היורד מן השמים
The Gemara raises an objection from a baraita to the assertion that eating meat was prohibited to Adam: Rabbi Yehuda ben Teima would say: Adam, the first man, would dine in the Garden of Eden, and the ministering angels would roast meat for him and strain wine for him. The snake glanced at him and saw his glory, and was jealous of him, and for that reason the snake incited him to sin and caused his banishment from the Garden. According to this, evidently Adam would eat meat. The Gemara answers: There the reference is to meat that descended from heaven.
The gemara seems to be saying that there was an exception because it was meat from heaven.
Why didn't the Gemara just answer that the meat which the Malachim served Adam was permitted to him because he did not kill it? This also seems to imply that Adam was totally forbidden to eat any meat at all.