Super clear video by Nicholas Tapia about how and were to find the beat.
Second part (just the whole song with the graphics to practice.)
Basic Tango Structure by Shlomo Lufer
The milongha rhythms by Shlomo Lufer
Tango and Musicality with Claus Springborg - Rhythm of Milonga
Musicality concepts
Tango Rhythm- Beats, Syncopat, 3+3+2
A fantastic post about the diferent orchestas and musicality in this link