Contact list no longer available in new Teams version

And now I've gone down the rabbit hole of trying to at least get the People app to show ALL of our people.  Apparently, it's bringing up my Contacts list that I went through the trouble of entering in manually but I need to get a company-wide directory list to sync into it, instead... so all of our end-users can utilize this.  We currently have the Spark (Openfire) app running on all computers in the company but, since the higher-ups want us to embrace Teams, that may be going away.  Huge sigh... it's a great app which works SO well - shows a full list of users and whether they're active or not... and we can message a group of people or all the people... more sighing.

But... I have no idea how to get a company directly to sync into the Teams People list automatically.  I'm searching and clicking on links from links... and finally had to close a bunch of browser tabs so my head wasn't spinning any longer.  Reaching the point of stopping ... but then I'm not making progress in trying to make this function at all.