Language translation problem (WMP)

I have site in 2 lang (eng and german).

In backend i defined acf field date_time…

Date format is defined: m/d/yy, DD

BUT DD is problem. He is alway in englis language (day in week). How translate in in other lang?

(i using wmpl).

THX

https://wordpress.org/plugins/acf-field-date-time-picker/