Cost to move from Deluxe to Premier Online

I purchased the Deluxe online version for my 2021 taxes (I have used the Standard online version the past few years). I activated my purchase and started my return but once my T5008 form was entered it will not let me proceed without upgrading to the premium version.

 

Last year's Standard online version did not do this and my tax situation is basically the same as 2020. I will eventually be filing 7 returns for myself and family and my purchase allows me 8 returns for my purchase price.

 

I can't seem to find out how much it will cost me to upgrade to Premiere online version and how many returns I will be able to file without extra charge once I pay the upgrade cost.