A pleasant day to you, Becca.
Let me share info on how the QuickBooks Online (QBO) App and Desktop versions work.
You don't need to connect them, you can utilize the QBO App and Desktop version at the same time. Just use the same credentials when logging in to both versions.
Also, I'll add this article if you want to permit someone to open your QBO account with specific access: Add and manage users in QuickBooks Online.
For additional questions about managing your QBO access, leave a comment below. We'll be willing to lend a hand. Keep safe, and have a good day.