To give the song a more intimate and folk-like feel, try using a fingerpicking pattern. Here's a suggestion:

Bridge: Am7 - Fmaj7 - G7 - Cmaj7

Chorus: G7 - Am7 - Fmaj7 - Cmaj7 G7 - Fmaj7 - Cmaj7

Thumb: C - E - G - C Index: 0 - 2 - 3 - 2 Middle: 2 - 3 - 2 - 0 Ring: 0 - 2 - 3 - 2

Here's a draft guitar chord sheet for "Alfonsina y el Mar":