You should be navigated to the Install Required Plugin page, which shows reqquired plugins list, all you need is clicking on the checkbox beside "Plugin" label to select G5 Core, G5 Staff in the list, then choose "Install" from the drop-down list at the top and then click "Apply".
You can do the same as installing, After you install successfully,you select that two plugins to active .
After you install & active G5 Staff plugin, G5 Core plugin successfully, the Staff settings start to display
The Staff items are included Staff post type, Staff settings, Overwrite Theme options for Staff
1- Staff post type are options register a custom post type for Staff items. It also registers separate Staff taxonomies for tags and categories
2- Staff settings are settings for layouts, gallery etc in Archive Listing and Single Staff
3- Overwrite Theme options for Staff are settings for layout, page title, header, footer, color and typography in Archive Listing and Single Staff. This settings overwrite the same setting in Theme option