Could you measure the speed using the Ookla Speedtest from the Microsoft Store on a Windows PC that is connected to the network with network cable.

What is the speed you measure?

Here, this is the result of the speed test from Ookla.

How is that computer connected to the network?

What is the brand and type of that computer?

I have a laptop which is connected through WiFi and it's a HP probook.

I asked you to use a computer that is connected to the network with a network cable. This is the only correct way to measure the speed of your Internet connection. 

Try wired and connect directly to the router/gateway to check the speed. Best thing is to check it when the installation person comes. They have special equipment to test.  But funny enough i didn't get the speed on my laptop (just was checking before him for fun). I tried another laptop and it gave the speed. The nic driver of my (expensive)laptop had issues. So, i would advise to try another device as well.

WiFi itself could be the bottle neck here. It depends on whether you are using 802.11 ac or ax WAP and that itself could increase the "speed" of WiFi. I'm not saying WiFi 6 is the ultimate solution but that in my experience, even for SOHO network, it gives better experience (not just speed). 

Even WiFi 6 and optimal transport i get only 300 Mbps down/up. And that's very good and i cannot find a way to make use of that goodness. That's why I said it's about experience (including the nerdiness feeling of having WiFi 6). Maybe i will Tweak it for fun to get more juice out of it (even if totally useless).

Wired i get 900+ download and upload bandwidth. Probably with a better router i can get more. I'm a heavy user (but no servers running) i can't make use of that. What i focus is on latency.