Exterior wall plastered from the inside -> smells strange

Good day everyone,

I am Chris, 26 years old and an electrical engineer. I have been living in my own home (single-family house) for a year and am currently renovating my entrance hallway. I try to explain everything as detailed as possible for me as a layman^^

My front door leads into a small entrance area (hallway) of about 2 x 1.4m. From the front door’s perspective, the left wall is an exterior wall. Straight ahead is a partition wall made of OSB boards, behind which is the kitchen. To the right, there is an interior door leading to the dining room.

There used to be a wooden paneling without insulation throughout the hallway, which I tore down a year ago. Behind it, on the aforementioned exterior wall, there is some mold. The wall has now been without any paneling or similar for a year.

Now I wanted to make the room nice again and cover everything with drywall. Since I read a lot that drywall on the inside of an exterior wall can cause mold if it is not 100% sealed, I canceled that idea before I made a mistake^^

So I removed the old plaster from the wallpaper, knocked off loose parts, and treated everything with primer. I let it dry for about 6 hours and then replastered the wall. It also turned out quite nice for the first time and especially holds well.
I plastered with Knauf MP75 and Rotband, about in a 2:1 ratio, since I heard that makes the plaster set better. So I first plastered ONLY the exterior wall from the inside. Otherwise, nothing else yet.

That was 2 days ago, and an increasingly strong stench is arising. It smells very damp, slightly moldy. That is certainly because I barely (almost not at all) aired the room. The reason is I cannot leave the front door open. The interior door to the dining room also cannot really be left open as I have a big dog who would surely take the opportunity^^ Now I am considering getting a dehumidifier so the wall can start drying.
By the way, the room is unheated!
A few hours ago, I placed a small fan heater in front of the wall and left the front door open. Not exactly environmentally friendly, but the plaster is now already superficially dry at the height of the fan heater. That was not the case before.

Basically, the questions are:
1. Is the smell understandable?
2. If yes, is it something serious, or better asked, will it come back once the plaster has dried?
3. Does using a dehumidifier make sense?
4. Did I do it correctly at all? :/ Apart from possibly missing insulation. The room is not supposed to be heated or warm. It should simply stay dry^^

For the last question, it might help to say that the house is from 1932. The aforementioned wall is made of clinker brick (about 38cm) and inside, I believe there are Ytong blocks attached (about 12cm). I could guess that under the old plaster, but I am not sure. So the wall’s structure from outside to inside is: clinker brick-(air?)-Ytong-old plaster-new plaster.

I hope I have expressed myself somewhat understandably. And thanks in advance

I'll put it this way, ventilate as much as you can, you've splattered a lot of water on the wall. When I applied rough plaster in my place back then, I believe the windows were wet on the inside every day for at least a week.

Wall is dry. Smell is gone. everything looks good^^

Wall is dry. The smell is gone. everything looks good^^

That the wall is dry on the surface does not mean that it is completely dry through.
If I were you, I would continue to ventilate regularly over the next few days.