Sign in to the you Keeper account,, and once you have supplied your email address and clicked 
you will be asked to supply your fido key;
Select "Security key", insert your key into a spare USB port, then click 
.
You will now be asked to type in the PIN code for your FIDO key;
Enter your PIN then click
;
You will then be asked to supply your master password;
Type in your master password then click 
and you will gain access to your Keeper account.