Blossom doesnt support NIP96.

If its a NIP-96 compliant server then you can add it to your media server list.

Of course users wont know if it supports NIP96 so just plug in the url for the server and trial and error.

https://i.nostr.build/GnhSULWpRRm8fotf.jpg
https://i.nostr.build/YQm07z7iu6yMqBVW.jpg