I am assuming you only want to add this dependency because you want to get it installed in OSGI but you don't have its use in your code.
Follow below steps to install the jar with project installation via maven:
1. Download the jar
2. Create a install folder if not already present in your project structure "my-project/ui.apps/src/main/content/jcr_root/apps/my-site/install"
3. Place the sling security jar in this install folder
4. Run mvn command to install project to AEM
5. Check if the jar is installed
Placing jar in install folder will automatically get it installed to OSGI once the package get installed. You do not need to add its dependency in the project now but will have to keep jar in your project structure.