This is the error I currently get when trying to "apt install" or "apt update" anything:

The following packages have unmet dependencies:
 omadac : Depends: mongodb-server (< 1:4.0.0) but it is not installable or
                   mongodb-10gen (< 4.0.0) but it is not installable or
                   mongodb-org-server (< 4.0.0) but 4.4.13 is installed

Here's the output from examining the DEB files downloaded from the TP-Link website:

$ dpkg-deb --info Omada_SDN_Controller_v5.0.30_linux_x64.deb | grep mongo
  mongodb-server (>= 3.0.0) | mongodb-10gen (>= 3.0.0) | mongodb-org-server (>= 3.0.0),
  mongodb-server (<< 1:4.5.0) | mongodb-10gen (<< 4.5.0) |  mongodb-org-server (<< 4.5.0),

$ dpkg-deb --info Omada_SDN_Controller_v5.1.7_Linux_x64.deb | grep mongo
  mongodb-server (>= 3.0.0) | mongodb-10gen (>= 3.0.0) | mongodb-org-server (>= 3.0.0),
  mongodb-server (<< 1:4.0.0) | mongodb-10gen (<< 4.0.0) |  mongodb-org-server (<< 4.0.0),

  @Indrek I have this exact same error while using Ubuntu, for now I went back to 5.0.30, I wish we could get an answer from mods

  @Fae Thank you for the response!

Personally I managed to fix it by unpacking the DEB file, editing the dependencies inside and re-packing it, then installing the modified DEB. I won't go into details here since the solution you posted is much more straightforward, but for the curious, there are instructions on the internet how to do this. Might come in handy if someone is deploying the installer using an automated process like Ansible.

Is this only temporary solution and new version will have fixed dependencies?

I was able to install omadac, but not able to upgrade system (without uninstalling omadac).

I haven't found any solution for this so far...

# apt upgrade

...
The following packages have unmet dependencies:
 omadac : Depends: mongodb-server (< 1:4.0.0) but it is not installable or
                   mongodb-10gen (< 4.0.0) but it is not installable or
                   mongodb-org-server (< 4.0.0) but 4.4.13 is installed

  @jrypacek I did what Indrek said, unpacked the DEB file, edited the dependencies inside and re-packed, Fae solution was fine but just for installing

Funny, I posted about this (albeit in the wrong section of the forum) and got hassled by some other user....

https://community.tp-link.com/en/business/forum/topic/541466

I'm hopeful that TP-Link will fix the dependency issue in the package as installing with ignore dependencies will mess up future system upgrades (as noted by another user in this thread).

@jrypacek @iamperson347 Beta of v5.2.4 of the controller software has been posted, fixing this dependency issue is listed in the changelog.

https://community.tp-link.com/en/business/forum/topic/542418

Edit: confirmed by examining the DEB package:

$ dpkg-deb --info Omada_SDN_Controller_v5.2.4_Linux_x64.deb | grep mongo
  mongodb-server (>= 3.0.0) | mongodb-10gen (>= 3.0.0) | mongodb-org-server (>= 3.0.0),
  mongodb-server (<< 1:4.5.0) | mongodb-10gen (<< 4.5.0) |  mongodb-org-server (<< 4.5.0),