Maiden Voyage almost demands the "Charleston" rhythm (Dotted quarter note followed by an eighth note). Set a metronome to 60 BPM. On beat 1, mute the strings. On the "and" of beat 2, play the chord. The PDF should have rhythmic notation examples showing how to lock in with a bass player who is walking quarter notes.
If your PDF is comprehensive, it might include a transcription of Herbie Hancock’s original piano comping from the 1965 recording. Piano voicings often lie flatter on the fretboard than guitaristic shapes. Try playing Hancock’s right-hand block chords on your top three strings. It will be awkward at first, but it is the quickest route to sounding like a pro. Maiden-Voyage-Guitar-Comping-Pdf-Download.pdf
Your strumming hand is stiff. Solution: Maiden Voyage should feel loose. Use a very thin pick (like a .50mm) or use your thumb. Let the chords breathe; you do not need to play on every single beat. Maiden Voyage almost demands the "Charleston" rhythm (Dotted