As per this Revenu Québec webpage: General Restrictions For The 2021 Taxation Year, you can’t file your return online if “Your social insurance number begins with 9, and no income tax return has been processed in your regard.”.
You will need to print and mail your Québec return to one of the following addresses:
Québec City
Revenu Québec
3800, rue de Marly
C. P. 25555, succursale Terminus
Québec (Québec) G1A 1B9
Montréal
Revenu Québec
C. P. 2500, succursale Place-Desjardins
Montréal (Québec) H5B 1A3
