Great question — answering as the UphillTech team:
The host controls this, not you. Zoom only shows the Apps button in someone else's meeting if the host turned Zoom Apps on for that meeting. Your own setting covers meetings you host. Two things to check on your side anyway. First, update the client. Linux builds lag behind, and the Apps button needs a recent version. Second, the host has to allow it. In the web portal under Settings, then In Meeting (Basic), Zoom Apps must be on. If the host turned apps off or runs an old client, no button shows for anyone. I hit this exact thing on Ubuntu last year. I updated the client and the button showed up in my own meetings. In a client's meeting it stayed hidden until they flipped the setting.
Full answer by Oliver Williams: https://superuser.stackexchange.com/a/1941124 (CC BY-SA 4.0).
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