Roles and Row Level Security

RLS:

Does your dataset have a column which matches or refers to your userid?

In the designer, click on Modelling and then Manage roles.

You need to create a role for each user, the DAX expression would be something like

[EMAILADDRESS]="[email protected]".

You might then have another dataset on your report which would be filtered like

[CUSTOMERID]="123456", assuming that when [email protected] logs in, they would only need to see data referring to CUSTOMERID 123456.

HTH