Studies are different than requirements because they allow multiple users to gain access under the same application. They also don't automatically apply to every dataset in the permission group and require you to add the datasets you'd like to work with.
It's helpful to think of a study as a group of users wanting to work with the same datasets to answer one conceptual question.
Every study is tied to an organization and can be created or referenced from any permission group which requires study approval, or from your workspace's Organizations tab.
You will probably create your first study when applying for datasets in a permission group. Click Apply and then New study to make your first one. Make sure to give it a name!
In the left bar of the study you will see a section to add users and datasets.
When adding datasets you can bulk add all the datasets in a collection to speed up the process.
By default when you create a study, you are assigned as the study's PI in the users list. Organization administrators use this field to better track their studies.
If you add more users to a study you can change the PI assignment. Over on a user's name and click Make PI to transfer. Note that once you change the PI you will no longer have the ability to change the PI assignment or delete the study.
You can add other datasets to this study by returning to the permission group and clicking Edit.
At some point you might have multiple studies (which might or might not include this dataset) which will all be listed. If one doesn't include this dataset you will be prompted to Add it, or you can Edit a study which already contains it.
After adding datasets to an approved study you will need to resubmit it to an administrator for approval.