There is no fixed capacity per Pro user. That's why it is called SHARED. It depends on how much users are using Power BI Service with shared capacity.
As per my feeling usually, it is around 3-5 GB.
Remove not used columns in data load. It means if you want to load Clients table, then prepare view/table on database side with needed fields. (Or while connecting to DB write SQL script where choose required columns).
Reduce the number of rows in a way I told step before (smaller period or any other filters, if possible).
Sometimes better if you will do maximum SQL JOINes on database side then on Power BI side.