Glyphs from font book preview do not work (appear as boxes/?? when copied and paste) MacOS Big Sur v11.6.8

I have downloaded a free font from dafont.com and installed the .otf to fontbook. I want to use the special characters/glyphs listed in the repertoire preview mode (they don't appear in any other preview). I know that when I cannot type a glyph from keyboard, you can simply use the preview like below to copy and paste while in any program, as long as you've selected the corresponding font for use within the app. Not the case for the depicted font... I notice that hovering over it that it does not have a U+ number. From experience, every font glyph that has that U+ can be copied and pasted. So how do I enable these characters without them to be used? If I have to get them to have a U+ code, How do I do that myself?