Conversion from PDF, and time signatures

Convert the attached file from PDF to MSCZ by sending it to MuseScore.
Open the MSCZ file in MuseScore 3.
The time signature is shown as 3 4. It needs to be 3 2. The score has "+" over the second half of each bar, and dotted minim rests.
Create a 3 2 time signature in the Master Palette. The time signature can't be dragged into the score, and the time signature in the score can't be altered.
MuseScore then reports "Not responding", and crashes out.
1. How can the time signature in the PDF be maintained in the MSCZ score?
2. Why are the MuseScore features inhibited in the converted file?