The First two movies, Beginnings and Eternal are simply a slimmed down version of the original series. The third movie, Rebellion, is entirely new content, as is the upcoming movie. Thus, either:

• Original series > Rebellion > Walpurgisnacht: Rising
• Beginnings > Eternal > Rebellion > Walpurgisnacht: Rising

Will both work fine, though generally the series is recommended over the movies due to them having to cut out some scenes to save runtime. Or if you want and don’t mind the repetition, you can always watch the series first and then all of the movies.

Magia Record series is a spinoff featuring a different main cast and can be watched any time after the original series/first two movies. It will most likely not be in any way mandatory watching before the upcoming movie.