It is possible that a problem with the local data within your Zoom application has caused the error on-screen message: “Failed to sign in. Please try again. (Error Code: 4)”.
How to fix Error Code 4
I found that uninstalling the Zoom application and then reinstalling it was the simplest way to resolve this issue.
The other option is to open File Explorer on your Windows device and locate the file %appdata%/Zoom/data then delete it using the appropriate menu item.
Using the Finder on a Mac, open /Library/Applications/Support/Zoom.us/data and find the file named ‘*.zip.us/data’. Delete the file.
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