Audio Synchronization failure

The "multicam" term is somewhat of a misnomer. As that is the main intended process for joining vide and audio files no matter the number of cameras involved. So yea, confusion is kind of expected.

For example, you can take ten takes with one camera, one external audio device. Put the media in a bin. Select all, "create multicam", and you'll get 10 different "multicam sequences" ... so each pair will be it's own 'sequence' ... essentially, a clip.

It does need to have similar gain levels ... so again, selecting the say lower level clips in the bin, raising gain, then doing the "create multicam" will work.

So you need to select the elements ... audio and video files ... in  the project panel bin.

Then "create multicam".

I'm only using one camera, but I tried a multicam timeline after reading your tip.
Synchronize is greyed out.
Moving back to the normall timeline, I now have + 19 dBs on the A2 track.
It synched the first clip, then it showed the same message again.
The audio is clear on both tracks. Can't understand this.

By the way, I forgot to mention:
Premiere Pro V 24.0 (build 58), running on a MacBook Pro 16", Apple M2 Max, 32 GB, Ventura 13.4

Premiere needs the audio to be relatively close in gain. Your A1 and A2 tracks have different waveform levels. Make one closer with gain applied in the Project panel, then it should work.

And you're using multicam to do the join, I hope? It's the 'correct' process in Pr for this work.