There are no lyrics so imagine each chord or slash is a beat, not necessarily a strum (they play quite a bit with syncopation throughout).
The C# isn't quite on the beat, but you should be able to hear where it hits relative to the C.
main progression
G / / / G / / / G / / / C / Bb /
G / / / G / C / D / / / G / / /
Breakdown jam:
G (sometimes with stops)
then:
C / / / C / C# / (several times)
C / / / D / / / (hold and then back to the main progression)
Transcribed by: Dan W.