There is a way to automate the procedure and have these courses automatically assigned to every new user that registers to your portal: the default group.
Just create a group, assign the course(s) you want to it and then through the Account & Settings -> Users tab, select it as the Default system group (1) .
That's it! From now on every new user that self register or is added by the administrator, will be automatically assigned with the default group's courses.
The same can be done for each branch that you have in your portal.
In most cases, every branch has its own course(s) that should be assigned to the branch members only upon their registration.
Just create a group for each branch and assign the branch's course(s) to the group.
Make sure that the course(s) assigned to the default group are assigned both to the group (1) and the branch (2).
Edit the branch and select the relevant group as the default branch group (1).
Every new user that is registered or manually added by the administrator, through the branch url, will be automatically assigned with the courses.