-> Go to Microsofts guide on how to create a Team: Microsoft has its own guide on how to do this.
Notice that in step 4 where you choose what kind of team you wish to create, choose Other. Do not choose Education. It is for primary school and you will not get a fully working team. Also take a look at Microsoft's help center for MS Teams.
Below you will find guides regarding the creation of teams that are special to UiO or not covered adequately by Microsofts guides.