How do I add a song from Spotify?

You bring the link. Copy a song, album or playlist from Spotify’s own Share menu, open the Memory, tap + and choose Spotify. Paste it in and the card appears. Tapping that card later opens Spotify; Lumoria never plays it.

Step by step

In Spotify, find the song, album or playlist and tap its … button.
Choose Share, then Copy link.
Back in Lumoria, open the Memory, tap + and choose Spotify.
Tap the paste button at the end of the field, or paste it in yourself.
The card appears under the field. Check it, then tap Add to Memory.

There is no search button to press: Lumoria goes looking a moment after you stop typing. Add to Memory only wakes up once the card is there, so what you approve is exactly what gets saved.

What you can pin

Songs, albums and playlists.
Links that start with open.spotify.com, and the short spotify.link ones.
Anyone’s playlist, not only your own.
No Spotify account and no Premium, on either side.

If no card appears

That doesn’t look like a link: the field wants a URL rather than a song name. Copy one from Spotify’s Share menu.
That’s not a Spotify link: an Apple Music link belongs in the Apple Music tile instead, and artist pages and podcasts can’t be pinned.
Link could not be resolved: the song may have been taken down, or the link may be incomplete. Try another one.
You’re offline: looking a link up needs a connection. Paste it again with signal and it will work.

What the card shows

The artwork and the title, in Spotify’s green on a dark card, with the Spotify mark beside it. No artist, no track count, no length: Spotify doesn’t hand those out without an account Lumoria doesn’t have, and a made-up artist would be worse than none. “Why can’t I search Spotify inside Lumoria?” explains where the line falls.

One piece of music per Memory. A Spotify link replaces an Apple Music playlist that’s already there, and the other way round.