signed out, signed in, re-installed still gives error: unable to link account.
If you experience technical problems I‘d highly recommend to contact the creative market support directly to get more precise and faster help. Please keep in mind to describe the issue you’re experiencing in detail (where do you want to link which account to? At what point you’re experiencing an error? You can also send screenshots).
Please follow the instructions here: https://support.creativemarket.com/hc/en-us
Hope that helps!