How to use "If so" properly

Is this correct to use "If so" in the following way?

I just want to make sure if I have completed the process of accepting the scholarship; If so, would you please provide me an official letter about it.

Best

the idiom and examples of usage may help: TFD

if so

if that is [the case]; if that is so.

'She might be late. If so, we will eat without her.' 'She is supposed to be all right. If so, we have nothing to worry about.'

Your sentence without too much alteration wcould be:

" I just want to make sure I have completed the process of accepting the scholarship; if so, would you please provide me an official letter about it."