My PrintShop 2 will not update to 2021 monthly calendar

As you no doubt know by now, Print Shop is no longer supported for the Mac. I don't understand what you are asking about a 2021 monthly calendar. Calendars are available from many sources. They are often provided as part of an email program. Others are available on the Apple App store. Just do a search. As to an alternative to Print Shop, you could look at Swift Publisher. It is a full featured desktop publishing program which does far more than Print Shop ever did. Since your question was so unclear, I am not sure if I have answered it.

Look at Swift Publisher 5 in the Mac App Store. There is a free trial on the vendor's website. It will not import your PrintShop files, nor will anything else, so Swift Publisher 5 is a means to redo your Print Shop documents in a supported application.