Updating your EndNote version to 21.4 should resolve this issue. Instructions follow for other versions.
No EndNote Workspace after Installation
After your installation, Macs do not prompt you to create a library. All you will see is a thin EndNote toolbar at the top. Solve this by creating a new Library, or opening an existing library. Printable instructions: at I don't see my LIbrary
EndNote 21 > New
Name the file or accept "My EndNote Library" as the name.
Select the Save as Package option and click Save
Permissions
If you have updated to a new operating system (OS), such as from Ventura to Sonoma, you may finds applications do not work because permissions have gone back to a default, and you need to allow permission to the applications again.
Sometimes you will be prompted for a permission change in EndNote, or in Microsoft Word. Click Allow, See an example of a prompt in Word below.
If you wish, you can give EndNote Full Disc Access, as you would for an Anti-virus Program. This will keep EndNote from requesting you to Allow every time you open the program. Note: Giving EndNote permission in Security > Automation, still does not stop Allow requests. Full Disk Access is the only permission level that works. If you are uncomfortable with this level, you can just acknowledge the Allow option when using EndNote.