Migration to Power BI / Services

Our company is planning to migrate from Qlik to Power BI (cost effeciency is mostly the case).
I have some basic knowledge of power bi and wanted to understand it abit more.
One of the problem we're running into is how our client access the reports we're created for them.

Using trial right now.
I can create a workspace with 'trial', premium per use, and pro as the option.

The workspace option for premium capacity, fabric capacity or embedded is unselectable.

I created the workspace as a premium per use, but i cannot invite others (external user - my personal email) to the workspace.

What do we need to be able to do this?
I've email our IT Admin for checking on our tenant with microsoft and see if we can invite external users.

Any suggestion on what we're missing so that i can invite external users to our workspace?