On inspection of the font "DIN Alternate" which is offered as "free" on various dubious websites, I was able to extract this information from the font file itself:
©Dutch Design: Albert-Jan Pool, 1995. Published by FontShop
International FontFont release
So, yes it would seem to be copyright, and I would assume you need to buy a licence. So, contact the publisher
Some of these free font sites don't seem to care if fonts are offered legally or not, which is why I would never use them. Other more responsible free font sites do display the licences, such as dafont, and fontlibrary. My suggestion would be only to use sites which actually refer to the licences.
One of these so-called "free" font sites, which I shall not name, offers this laughable disclaimer.
By downloading fonts from our site or using them you agree you have
read and understood that the font or dingbat copyrights belongs to the
designer of the related product. In cases where there are no copyright
notices, you need to assume that the font is copyrighted. Use of the
fonts is at your sole responsibility. We do not take any
responsibility and we are not liable for any damage caused through use
of the fonts . . .