What is expected in a masters thesis for Phd admission in Europe by admission committee in Number Theory
From a Finnish perspective (the department was focused on analysis, not number theory):


No, it is not expected for you to have original publications from your master studies, but if you have them, great! I am not sure how a publication in a predatory or very low quality journal would be taken; in the spirit of being careful, I suggest not publishing unless you are certain it is a decent result and a decent journal. Or maybe only publish a preprint.
A good master's thesis need not include original research, but it might. It shows a clear grasp of mathematical thinking and good and non-trivial proofs. An excellent thesis has original work, or does the same as a good one in a very demanding subject.