To get a developer certificate to make apps for the Mac the person has to apply for it and have a choice of an Individual Membership or a Business Membership. The individual membership is much easier and will display the name of the person, while the Business Members requires documents to be provided to verify the business name. Verification of an individual is done simply by them providing identification such as a government issued ID card.
When you go to > System Settings > Privacy & Security you have the option to install apps from only the App Store or from the App Store and Identified Developers. The Identified Developers are those that have been registered and you will be able to install those apps even if you do not download them from the App Store.
As for being malicious, it is definitely not a virus and cannot access other information on your Mac because all apps are sandboxed and can only access its own data unless you give it permission to access your Photos, Contacts, or other personal information. In that case you would need to determine if the app really needs additional access to your information. Some apps do need to run on startup, which is why you are seeing that alert, but I prefer not to use apps that run constantly in the background unless I really need it. The problem with many apps that run in the background is that some will conflict with others and may not work well with future OS updates unless the developer keeps them updated. You can see these background apps by going to > System Settings > General > Login Item.
Bottom line is if you find the app useful then allow it and if you do not, then just remove the app. Getting Apps from the App Store are easy to remove, since all you have to do is move them to the trash. Some installers simply show a picture of dragging the app to your Applications folder and those are fine and can be easily removed by dragging it to the trash if no longer needed, but try to avoid the other installers that will install files in multiple locations that are hard to find and remove. Those installers usually ask for an install location.
