There are two ways to share multiple files with reviewers
1. Multiple Select
To share more than one creative, select the files with the Shift key and click the share icon in the top right corner. The lower half of selected files get highlighted in dark grey. Emails with specified access to all shared files get sent to all reviewers.
2. Share Folder
Create a new folder, right click and select the Share option. Similar to Sharing Files, the Share With window gives you the options to Get a Shareable Link or Invite Users. Options to Disable Download and Comment Without Logging are not available in the case of shared folders. Reviewers get access to all files and folders inside a shared folder.
If you want to give your teams access to upload files to your storage and share creatives with reviewers, use Shared Workspaces