If you're using a non-subscription version of Office to edit a document at the same time as others, you may receive a notification to switch to Office for the web. This is because your version of Office does not have many of the modern capabilities to seamlessly co-author in real time with other users. Office for the web is a free version of Office that has these capabilities and is a better choice to reach your goals.
If you frequently perform this task, contact your IT administrator about moving to Microsoft 365 for a better experience on Office desktop apps for Windows and Mac
You can disable these notifications by going to File > Options and selecting Always use this app to co-author on documents.
Note: If you disable the notifications the file will just open on Office desktop without suggesting Office for the web and you may experience issues with real-time coauthoring.