Pro Plan and Sharing

My apologies, I did not scroll through the myriad of questions/answers here completely.

I recently upgraded from the free plan to the pro plan, in hopes of developing something that can be shared and used by others in the office. My understanding is that with the pro plan, up to 10 collaborators can be sent sheets, etc. to where they can enter data into the sheets.

I seem to be getting stuck on the sharing of a sheet, and methods of sharing I have used keep directing me to purchasing additional licenses,

What am I doing wrong, and what do I need to do to share as I have noted.