Oh dear, Wer beat me again. Cool.
"Date Taken" is generally put into the [Date] field in MC. You can format that any way you want using the
FormatDate() function.
For your requirement: Formatdate([Date,0], yyyy-MM, )
These days, for new image imports, MC should set the [Album] field to the Date Taken, which is also put into the [Date] field, for all formats I believe. Just take note if that happens. That is used for the default Albums View in the Images section of the Navigation Bar. I don't think the [Album] field can be formatted with the FormatDate() function... No, it can't, as it is just a text (string) representation of the [Date] value. Raw date values are decimal numbers.
Regardless, if your View is using the [Date] field to group files, that can be formatted with the FormatDate() function.