Click the Signature button, Outlook hangs and you are not able to add a signature.
When you install an Office Subscription with that build or higher, it will automatically remove the pre-installed Microsoft Office Desktop apps.
Uninstall the pre-installed Microsoft Office Desktop Apps:
Right click the Windows Start button and click Settings.
Click Apps, and then click Apps and Features.
Choose Microsoft Office Desktop Apps and click Uninstall.
Restart your PC. And check the issue.
Run a repair of Office to make sure everything gets fixed.
If this method is unsuccessful, follow these steps to remove Office setup registry keys are still incorrectly remaining in the registry:
Note: Before you edit the registry, we recommend that you make a back up of your registry.
Open a Run window.
Type regedit and click OK.
Press CTRL + F and enter 0006F03A-0000-0000-C000-000000000046 into the search box, then click Find Next.
Delete the key by right-clicking on the entry and click Delete.
Press F3 to repeat the search until no more registry keys are found.