You run into the error 'Failed to activate the license' when attempting to activate your license. User account licensing (logging in when activating) and by extension the invitation function doesn't work if you are using a very old version of a product (prior to 2017) or an unsupported tool (eg. MySQL Compare) so if you have been invited to use a license in the customer portal and you try to activate it you will get the error message:
To activate the license you will need to log in to the customer portal and remove yourself/the user. Then you can install the license using a product installer which you can download from the website and activating the license key.
To remove an allocated user, click on the Remove button alongside their details in the list.