This study is for patients who have been diagnosed with grade 1 or 2 recurrent or metastatic endometrioid endometrial cancer. The investigational drug used in this study is ipatasertib. Investigational means it has not been approved by the United States Food and Drug Administration (FDA). The marketed drug used in this study is megestrol acetate (MA). Marketed means the drug has been approved by the FDA for sale and use in the United States. The primary purpose of this study is to compare the progression free survival of the combination of ipatasertib with MA to MA alone among women with metastatic grade 1-2 recurrent or metastatic endometrioid endometrial cancer. Patients will be randomized to either of the two treatments. Randomization is like flipping a coin, essentially meaning that each option has an equal likelihood of being selected. The drug is given to participants orally. Participants can expect to be on this study until disease progression or adverse events prohibit further therapy.