I have an online subscription but it doesn't link to my mobile app. Im very new to this, should they link up?

Hello S-Burgessjoinery, 

Welcome to the Community page, 

Yes when you log on the website or app it will be the same account.

So when you log onto your account on the website with your user name as email address and password it is the same user name so email and password you use to log onto the app. 

Make sure you have download the correct Quickbooks app- so the self-employed one.