"Some packages could not be installed." - why?

Question

linux

I install MongoDB according to this instruction on debian 10.
When I get to "apt install mongodb-org" there is a following. mistake:

# apt -y install mongodb-org
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 mongodb-org : Depends: mongodb-org-server but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

But at the same time on debian 9 the installation was successful

Answer 1

Learn English so as not to install software according to Vasyanov's precepts.
MongoDB has its own deb repositories for Debian, instruction .

Answer 2

Because the instruction was written specifically for Debian 9. Debian 10 has its own (other packages), with other versions, and what is required in the instructions for Debian 9 is simply missing in the repository from ten. If knowledge of the language allows, then yes, in this situation it makes sense to use the official instructions. There she is quite sane.