How do I add not native extensions in Drupal, I was using WordPress where I know how to do it but recently moved over to Drupal.
You can create a folder somewhere outside the main tree, so that when you upgrade core you don't overwrite your extensions, and then in civi under Admin - System Settings - Directories, you put the file path to that folder where it says "Extensions Directory".
If you already have some other extensions installed, they might have gone under sites/default/files/civicrm/ext, in which case you want to move those to your new folder too. You could put everything in sites/default/files/civicrm/ext, but it's easier to manage outside the tree. See also https://docs.civicrm.org/sysadmin/en/latest/customize/extensions/#enabling-extensions