Hmmn. OK - here's the process...
If you don't already have a Legacy app and file structure installed, look for a copy of the installation file (v6.25.x) on your system, or download it (which is NOT recommended) from a third party repository such as https://filehippo.com/download_evernote/history/
Once the Legacy file structure is in place
🔹Select: Evernote > Options> Open Database folder
🔹Drag and drop your .exb file into the database folder.
🔹Close database folder window
🔹Select: Ctrl+Shift+E while viewing the login screen.
🔹Select your .exb file
This will create a new folder on your Desktop that contains a separate .enex file for each notebook (that has notes) within the account. EDIT - you'll then be able to import those into the new version or upload them to another client.
(adapted from a 2016 fix described in the Evernote Forums) -
The EXB file format is a modified MySQL database. Suitable file viewers and database managers will also help rescue data if ncecessary.