Sorry, but a Raw repository does not have any support for associating multiple assets with a single component. Probably the best you can do is choose a folder structure that keeps the assets together, then use a REST API query to get a list of all items in that folder for download.
Assuming you are on pro you can certainly use tagging to identify the artifacts. Downloading them all would still require using the rest api to get a list of the tagged artifacts and then downloading them one at a time.
I believe you have to use the REST API to create tags before you can apply them. If the user has access to the Admin > System > API page they could use the swagger api client page to create the tag from the UI but there is not a way to create tags from the UI otherwise.