How to prevent pushing directly to Master branch in AzureDevOps

User from a group like Build Administrator can access the project from Azure Devops. I need to control the user in that group to upload the file directly to the master branch. The user can manually upload files to all branches except Master. Because my master branch is based on Pull request. How can I implement this? Does it need any permission?

There are a few critical branches in your repo that the team relies on always being in good shape, such as your master branch. Require pull requests to make any changes on these branches. Developers pushing changes directly to the protected branches will have their pushes rejected. Thus, following this doc: Improve code quality with branch policies to protect your master branch.

In addition, be reference to this doc: Allow bypassing branch policies without giving up push protection, please note that these 2 permissions(Bypass policies when completing pull requests and Bypass policies when pushing) shouldn’t be granted to your mentioned Build Administrator group for master branch. See: Set branch permissions for details.