Insect and Spider Identification: ID on this bug?, 3 by WeirdBug

WeirdBug wrote:
A couple of days ago I started seeing this bug near the entrance of my apartment (inside of it). I suspect that there is a lot of them, as I\'ve already seen >10 in the last couple of days.

I live in Zagreb, Croatia

As I\'m not sure what it is (I have pretty much zero knowledge about bugs), I wanted to ask someone to ID it.
From my calculations it\'s about 0.3 cm in size (most of the photos were taken with a large zoom, so I put one with no zoom in for reference).

Thank you all in advance!