Hi there, emmanuel-parcelh.
Thank you for posting here in QuickBooks Community. I'll provide information about the Apps tab in QuickBooks Online.
QuickBooks added the Apps menu on the left navigation bar. However, this feature is not yet working in some international versions of QBO. With this, I'd suggest clicking this link to verify if your country is supported by the QuickBooks apps: https://quickbooks.intuit.com/app/apps/home/. Please select the Country drop-down arrow to see regions.
If your country is on the list and you get the "404 page not found" error, I'd recommend using an incognito browser when logging in to your account. This is to rule out the possibility of a webpage issue, and private browsing doesn't store local files or cache.
You may use the following shortcut keys below:
If it works in incognito, I'd recommend clearing the cache of your regular browser. This removes the history or log of sites so you can start with a clean slate. If the steps above didn't work, use another supported browser as an alternative.
I'd also recommend visiting our QuickBooks Blog. This way, you'll be guided with updates and newly released features in QuickBooks.
In addition to this, I’d suggest checking out our Help articles page. There, you can browse some useful articles that serve as your future reference for your future tasks.
If you have any other additional questions about this topic add a comment below. I'm here to get back to you as quickly as possible. Have a good day!